MIDI Merge: toggle between modes deletes notes

[PhilSchroeder]

PT 2018.4 and all previous releases dating back to PT11 (roughly 6 years)

When composing with my USB/MIDI keyboard, toggling MIDI merge on/off between overdub and overwrite modes, PT will inadvertently delete notes in my Instrument or MIDI track. If I catch it in time, I can easily undo. If I don't, and the page is scrolled to a place well into my session, then I lose lots of data earlier in the session.

Yes, I can usually reconstruct it from saved sessions, but this is a HUGE INCONVENIENCE. I cannot believe I am the only one who has ever experienced this. This has been going on since 2012. I've reported it to AVID many times and they don't seem to have ever heard of it.

Has anyone seen this?