With compile option -DCMAKE_BUILD_TYPE=DEBUG
If you left-click and drag on the timeline you will eventually get negative numbers. On my machine this happens around ~5m19s at 140bpm. This is a bit early for the counter to overflow. It doesn't happen when playing, only if you click the timeline at a certain intervals. It looks like the computation is done by a too small integer when clicking the timeline.

To reproduce:

• On a debug build. -DCMAKE_BUILD_TYPE=DEBUG
• In Song Editor, zoom out to 12.5 or 25%
• Click on the timeline and drag. The time may or may not overflow to a negative number at intervals.