Hello world ;
It’a a well known problem in ardour that is still in the 6.5.0 - 64 bits on windows 10. I saw it on linux on old release. (see bug ID 0008385 for example)
- In a bugged region, when I put the time cursor on a note (auto snap both cursor and note on bar to be sure of sync) then the note is ignored and the next ones are played.
- It appears at the begining of some buggy regions (note not played nor seen) but also at the begin of loops in those regions (note seen but not played).
- It seems like every note of the region is a bit left-moved (before the snap grid).
- This bug is duplicated to duplicated regions (linked or unliked).
- When another region is created from scratch and midi note of the bugged region are copied to this new one, then the bug is not copied. (so this is workaround #1).
- Then I think the bug is linked to the region.
In this example (extract from test20210105.ardour file), first bugged region is General MIDI Synth-4.1. Duplicated to MIDI-5. The region MIDI-1 is ok.
<Playlists>
<Playlist id="3646" name="MIDI.1" type="midi" orig-track-id="3607" shared-with-ids="" frozen="0" combine-ops="0">
<Region name="General MIDI Synth-4.1" muted="0" opaque="1" locked="0" video-locked="0" automatic="0" whole-file="0" import="0" external="0" sync-marked="0" left-of-split="0" right-of-split="0" hidden="0" position-locked="0" valid-transients="0" start="290680" length="1587600" position="88200" beat="4" sync-position="290680" ancestral-start="0" ancestral-length="0" stretch="1" shift="1" positional-lock-style="MusicTime" layering-index="0" tags="" contents="0" start-beats="13.182766439909301" length-beats="72" id="15554" type="midi" first-edit="nothing" source-0="8758" master-source-0="8758"/>
<Region name="MIDI-1" muted="0" opaque="1" locked="0" video-locked="0" automatic="0" whole-file="0" import="0" external="0" sync-marked="0" left-of-split="0" right-of-split="0" hidden="0" position-locked="0" valid-transients="0" start="0" length="264600" position="1764000" beat="80" sync-position="0" ancestral-start="0" ancestral-length="0" stretch="1" shift="1" positional-lock-style="MusicTime" layering-index="1" tags="" contents="0" start-beats="0" length-beats="12" id="16769" type="midi" first-edit="nothing" source-0="16767" master-source-0="16767"/>
<Region name="MIDI-5" muted="0" opaque="1" locked="0" video-locked="0" automatic="0" whole-file="0" import="0" external="0" sync-marked="0" left-of-split="0" right-of-split="0" hidden="0" position-locked="0" valid-transients="0" start="290680" length="1587600" position="2116800" beat="96" sync-position="0" ancestral-start="0" ancestral-length="0" stretch="1" shift="1" positional-lock-style="MusicTime" layering-index="2" tags="" contents="0" start-beats="13.182766439909301" length-beats="72" id="16805" type="midi" first-edit="nothing" source-0="16803" master-source-0="16803"/>
</Playlist>
</Playlists>
The start-beats=“13.182766439909301” seems strange to me when on Midi-1 it’s =“0”.
So I set it to 0 and the bug disapears. But the notes are moved to the right.
I just have to replace them manualy. (workaround #2)
I did it but I don’t know the consequences of manualy editing that file. Do it at your own risks 
You can also move the region about 1ms later (workaround #3)
Hope it helps
Wish you some good vibes
Jerome from LesPartagesDeBarbu