Ibus + m17n stops working after lock-screen

Hi,
this is a problem I have been able to reproduce several times on several laptops.

1) I have 2 keyboard layouts (say US + amharic (sera m17n)).
2) Everything works fine and I am able to switch between the two layouts.
3) I am on an empty workspace
4) I lock the screen.
5) I unlock the screen. (even with fingerprints)
6) I see that the "amh m17n" layout is not working anymore. It is not in the notification area. Nor wan I switch using keyboard shortcut.

Step "3" is really important since as soon as the focus is on a "keyboard aware window" the layout works fine again!
For example if you have an editor open in full screen, the bug will not occur. More precisely it will happen but as soon as the focus is on the editor window the layout is working again.

It's almost funny, for example after the bug occurred you may simply hit the window key, as soon as you click on the search area the two letters come back in the notification area.

It does not occur when using two non-m17n layouts.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ibus-m17n 1.4.2-1
ProcVersionSignature: Ubuntu 5.4.0-52.57-generic 5.4.65
Uname: Linux 5.4.0-52-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.10
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Mon Nov 9 11:23:42 2020
InstallationDate: Installed on 2020-09-24 (46 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: ibus-m17n
UpgradeStatus: No upgrade log present (probably fresh install)