P: Filmstrip is covering / overlapping filter- and breadcrumb bar

"already tried all this....but to no avail..."

Did you try resetting preferences?  http://www.lightroomforums.net/showthread.php?25197-Resetting-the-lightroom-preferences-file-updated  That has helped some who have these symptoms.

already tried all this....but to no avail...

Thanks also, Nikita. That fixed it for me too. First time I have experienced this issue in years of use of Lightroom. I believe I triggered it by some combination of turning off and on tabs along with switching screen mode from "full screen with menu bar" back to "normal", but not exactly sure. I think the bug must reside in the screen mode functions, as I had not previously paid much attention to screen modes - using loupe view with normal screen mode virtually all of the time.

I must be missing something very obvious, but my Window menu doesn't have "Show Top Bar":

Hi,

I was able to reproduce this and have logged a bug for the same.

@188115, it is Window > Show Top Bar. You have a Window menu next to Help.

Thanks,
Smit Keniya
Adobe Lightroom Team

By Window > Show Tab Bar, is that (in English LR) Window > Panels > Show Filmstrip?

That did the trick, Nikita. Thank you so much for the tipp!

"I'm confident that Adobe will fix the issue in a later update."

Unfortunately, based on experience with other bugs, it might be a very long time before this is fixed (or it might be fixed in the very next release).

there is probably a bug in Lightroom on mac (at least in Sierra). When Window -> Show Tab Bar is checked and one restarts Lightroom the upper part of the filmstripe is cut. To resolve the issue one has to unselect Show Tab Bar and restart again
the cut filmstripe you can see here https://forums.adobe.com/thread/2214640

It's like this, whenever I open LR since a couple of days. Can't replicate, what I did before that started to happen. Sorry!