Unread messages trackbar & Jump to first unread message button don't show on a specific channel

Hey, I've joined a 8k+ users channel, muted it, and now the trackbar saying "Unread messages" in the chat doesn't show anymore in that specific room. Also, the "jump to first unread message" doesn't appear anymore in this one room aswell.
I tried to revert back to default notification, put it noisy, mention only… nothing fixed that.
The "Unread messages" trackbar still shows in ny other rooms.
Is that a bug?

I'n using version `1.0.0 [40100000] (F-fca669ff)` from F-Droid, Matrix SDK `0.0.1 (fca669ff)`, olm version `3.1.2`.