bug when selecting tabs (Mac)?

[Elementari]

SB 8.4.0 / FF MacOS (Sonoma); 147.0.2 aarch64

I can only select tabs like this:
CTRL-down, LeftClick on Tab. --> now adjacent tabs that I move mouse over get blue frames.
When I left click on another tab, nothing happens.
I must right click on any tab. Then I can (a) do sth. according to the context menu, or (b) click outside of the context menu to end the selection, or (c) move the tabs via drag and drop (after which they will still be selected, requiring (b)).
This is counter-intuitive, but it works.

However, I am unable to select non-adjacent tabs (tried opt/cmd/ctrl/shift).

situation has been like this since I started using SB, years ago. tab group indent is set to one level.