Shift modifier not working/recognised in conjunction with other modifier keys when inside Zellij session

[blixenkrone]

Basic information

zellij --version:
0.41.1

stty size:
78 150

Issue description

Whenever I am inside a zellij in any terminal (tried 3 different ones), the shift modifier key is not picked up as a modifier key, when used in combination with others.
This is mostly an issue when using terminal editors like vim, since I have a keybinding with shift+alt+s to do :w or write_file.

As the most minimal example, a use case flow would be:

• I can write uppercase letters ie. ABCD with no issue
• I can not write my files with the key combination of shift+alt+s. Only alt+s combination is picked up.

If I am not inside Zellij, I can do above use flow without issues. The bug seem to only exists when I am within a zellij session.

Minimal reproduction

Terminal: Ghostty
Editor: Helix
1 Enter a zellij session
2 Open a file with Helix (or vim)
3 Hit shift+alt+s
4 Only alt+s gets picked up.

Extra relevant information

1 No /tmp/zellij-log file was produced when running with $ zellij --debug for some reason.
2 I don't think it makes sense to show this in a video recording, but I am happy to record one if needed.

Thanks for a great tool!