Nightly Flatpak on Wayland on Ubuntu 20.04 does not show the timeline time tracker / cursor / caret

[Russell-Jones]

Guidelines

• I have read the guidelines.

Version/Commit hash

Version: Build type: CMake Release build (debug level 1), 64 bits Compiler: GCC 11.2.0(Tenacity) wxWidgets: v3.1.5 (gtk v3.24)

Describe the bug.

(note the version field is blank in Help > About Tenacity > Build Information. There is no Commit Id field that I could find)

1. flatpak run org.tenacityaudio.Tenacity
2. Open > some.mp3
3. Click the Play button
4. The cursor/caret/marker does not move unless the UI is interacted with
5. close Tenacity
6. set GDK_BACKEND=x11
7. flatpak run org.tenacityaudio.Tenacity
8. Tenacity does not start (no error is output, the application just exits.)

Expected behavior

The cursor follows playback.

OS

Ubuntu 20.04 / flatpak from oci+https://tenacityteam.github.io/tenacity-flatpak-nightly

Additional context

The same warning is output both times Tenacity is started.

Note that the directories 

'/var/lib/flatpak/exports/share'
'$HOME/.local/share/flatpak/exports/share'

are not in the search path set by the XDG_DATA_DIRS environment variable, so
applications installed by Flatpak may not appear on your desktop until the
session is restarted.

The flatpak build shows an issue rather like audacity/audacity#459 which is ascribed to wxWidgets/wxWidgets#17820
This can also be seen in Audacity 2 on Wayland, though setting the backend to X11 works around it.

This issue is not a duplicate

• I have confirmed this issue isn't a duplicate.