P: Window Sizing Problem

Exactly same thing happens to me, along with starting up in near full screen mode even though I've previously made the LR window smaller. 

I have the same problem. Mac, OS/X 10.15.3. 

Plus, whenever I view a photo in full screen (by pressing F), the LR window goes to full screen after I close out of full screen via Escape.

Different strokes for different folks I guess, Carlos.  While I have LR maximized when in the Develop module, I have lots of reasons to to want it to open full size at every launch.

It wasn't there in 9.1, so rolling back to that might be an option for you.  That's what I did.

Very simple, it is a bug and its is not the way it should be.

Any way I am used to have many windows filling my screen I have a favorite size for the Lr windows, always 10 photos per row, allway at my favorite size per photo preview.

And I use many plugins that opens their own windows.

I finally I don't have 2 monitors, but in that case my main monitors will be in the same way I always use and the secondary used for preview a single photo. 

Thanks for your suggestions they are simple workarounds for a BUG. 

Regards.

When I'm annotating photos with metadata or looking up photos in response to email requests, I often have another app open side-by-side with LR, e.g. a Web browser or an email message.

Question: why would you WANT the window smaller than the size of the screen? I don't understand wanting that. I use 2 monitors, my iMac with the Grid View (as big as possible, but not Full Screen), and the 2nd monitor with "Full Screen, Loupe-Normal". PS-moving a window around to get at what's behind it is completely inefficient, use Command-H to hide it. -former Mac IT Pro.

On the contrary, I noticed it since the moment the app update itself.

My Mac OS is Catalina latest version.

Tried to reset preferences, but did not help.

Had not noticed this but I am on OS 10.14.6 with LR 9.2 and it happens on my iMac

I see it too on 10.14.6. Logging a bug with the team for Mac only.