There is a nice demonstration online which shows how to synchronize a Harrison Mixbus project to the imported recording of a human performance. In the past I used it to do similar things but with recent changes of Ardour 7.x it seems no longer to work the same way. Can someone help me with something similar using Ardour 7.5?
This has not been happening for anyone that has used it so far. We can’t fix it without either that session archive and/or an actual stacktrace. So archive the session, attach it to a bug report and let me know that you’ve done that.
One thing you should be aware of: because the tempo mapping design tries to obey what is known about human performance, there are limits to how much you can speed up/slow down by. Wildly dragging the mouse will result, in many cases, in poor results and maybe even strange behavior. The goal is to start with a tempo that is roughly correct and then adjust the grid in relatively subtle ways.