DJPro 5.1, MacOS.
Expected: when DJPro is playing and Link enabled, changes of tempo in the playing song should update the overall Ableton Link tempo when one of the DJPro decks is the master BPM source.
Actual: DJPro forces the playing song to whatever the starting BPM is by adjusting the pitch slider every bar.
Extreme example: Queen: Don’t Stop Me Now. https://youtu.be/cdLuld8qhAM
Wow, that looks wild. Nice work in figuring this out and finding such a good example 
Hope it will be fixed soon 
Hi @Rob_Grimes, thanks for sharing the video, this is very helpful.
Thanks!
My video is using a local copy of the track, but I have confirmed it also occurs for both Tidal and Apple streaming versions so you can pull the track from any service and see this behaviour.
I can confirm I am running the latest version, 5.1.3 and the issue persists.
I’m running MacOS Ventura 13.2.1 on an M1 Pro.
Thanks for the additional info @Rob_Grimes. I’ve sent everything to the engineering team for further investigation. I’ll report back here when I have news. Thanks!
I have the same experience, was going to post the same problem. Thanks.
The sync is automatically turned on when enabling the Ableton Link, causing almost any song to jump. And the looper also follows some of the same patterns.
I am trying to get SoundSwitch software to use Ableton Link.
Wow and it is like this since. Just tried the mentioned song and it is awful.
@Slak_Jaw Any updates on this topic? Or the reason behind this issue?
I thought about starting to use Sound Switch with djay pro, but it would not be possible because of this issue.
Thanks!
Yes disappointed about any progress here. Even having DJ Pro send out a simple MIDI clock would work for Sound Switch and other scenarios where you want external things to just follow the music without relying on audio beat detection solutions.
came here after experiencing this using djay at a wedding gig for the first time - it’s really bad, it took me a while to figure out what was going on, and had me questioning my decision to ditch rekordbox.
Not sure if it was exactly what you guys have experienced - I’m using lightkey, and after spending hours programming light scenes and looking forward to them syncing nicely, I realised when I was hitting sync in djay, it was syncing to whatever bpm lightkey thought it was via abelton link (and it was lagging sometimes), and not the active track in djay - insane! the ableton link bpm should always be at the bottom of the heirarchy, not the source of the sync bpm!!
this is a huge disappointment, but surely fixable?
I noticed that too. I also wanted to synchronize lighting software with Ableton Link. But DJay then behaves as if the lighting software is the master. That may make sense if you’re pairing it with software that also plays music.
But it should be possible to turn this feature on and off as an option.
Experienced the same, it is a bummer. Hope it will be fixed soon.
okay I found a pretty handy workaround for now: Wavesum makes machines understand music.
works well. not quite as accurate as ableton link (when it works like it should) but there’s no way for it to screw with your sync in djay
Thank you for the suggestion, I will try for sure! 
Hello everyone, I spoke with engineering regarding this.
Please test with this information, and if turning Link on first in djay doesn’t work as described, please record and share a short video of this. Thanks!
@Slak_Jaw I’ll refer you back to the video attached to the original report at the top of this thread. Here, no other software using Link was ever started (i.e. it stays at 'Connected Apps 0 in the link dialog), yet the pitch slider is moving all over the place - the track is syncing to some invisible external BPM source. This doesn’t happen with Link turned off but Sync still enabled.
Hi again @Rob_Grimes, our team did a deeper analysis on your video.
You can imagine Ableton Link as a straight beat that djay automatically syncs to. For songs with a straight beat grid it should work as described above. However, for songs with a dynamic beat grid, like “Don’t Stop Me Now”, djay tries to sync the grid of the song to the straight beat of Link. Since the grid of “Don’t Stop Me Now” is dynamic, it will adapt it frequently.
Right now this is the expected behavior. If there is other software that listens to Ableton Link, we don’t want to sync their output to these drastic beat grid changes. To help us improve on this in the future, perhaps you can explain what behaviour you would expect or prefer in this specific case with a dynamic beat grid? Thanks!
Hi @Slak_Jaw, I agree Don’t Stop Me Now is a dramatic example. Main issue is that any track that has some kind of BPM change just doesn’t work, even if the grid itself is straight either side of the BPM change.
Here is a more recent example - LF System Afraid To Feel. I would expect the Link tempo to be bumped up to 128BPM at the point we reach that point in the track. Instead, DJ Pro makes a dramatic pitch change which basically destroys the track.
The ideal would be a setting that just says ‘DJ Pro master deck always sets the BPM for Link’; this is perfect then for any software that just needs to slave off the current playing track BPM like Sound Switch, WTools (Wolfmix), external Drum Machine etc.
Just to add, running the same kind of scenario where an Ableton Live track has a BPM jump in a track and DJ Pro is set to sync, Ableton Live updates the Link tempo to 128BPM and DJ Pro follow it, so there is an inconsistency there as well.
Thanks for the additional input @Rob_Grimes. I’ll pass this onto the team…
I tested this out. First, I started DJay and turned on Link. Then I did the same with the lighting software.
It actually works a little better this way.
But it’s still not ideal.
The best solution would be to have a lighting mode. In this case, DJay should behave as if Link were not turned on. It should only send the current tempo and beat. Otherwise, it should do nothing.
Thanks for the additional feedback @MichaFalki. I will pass this on.
