playhead out of sync on JACK

since a week or so I recognize that on the current builds (cairocanvas as well as master), the playhead runs out of sync with the timeline when the sync is on JACK. It does not matter whether another piece of software is on the other side of JACK or not. It’s as bad as the playhead being behind a quarter of a bar after approx. 26 bars. That is a noticeable difference. It’s also bad because when you stop and play again, you get the last quarter of a bar repeated.
Has anybody seen that kind of behaviour before? As I said, the behaviour goes away, when I switch off JACK as an external timecode.

I have tried several builds (origin/cairocanvas, origin/master, 3.5.357) however, it seems that this is related to something different because at another test yesterday, I found, that the behaviour suddenly went away even with origin/cairocanvas. I guess I need some more testing to see whether this may be caused by some other config of my system.

What build do you have? I have 3.5.357 and I don’t have this issue. Did you change anything else around the time this started happening? Different JACK version, anything at all?