So, 10 years later and the bug is still there. Tested on 6.28 x64 and 6.29RC7 x64, the screenshot is from 6.29RC7.
This example is
Sitala on track 1, with sends to 16 tracks.
Also, the tooltip flickers quite a lot.
Hopefully relevant specs:
Win10 20H2 x64, 1920x1200 @ 60hz, NVidia GTX 970