Save game thumbnail problem in 5.0.9

I am experiencing the following issue with 5.0.9. I had used 5.0.3 for the development of my previous project (Yet Another Hero Story)  and I kept the 5.0.3 version up to the point of the game release.

Now I am working on a different project and I decided to start it in 5.0.9 right from the start. Everything works fine, except the save thumbnails. 

Whenever I save, I get a black thumbnail. FYI I used the exact same menu scene as in my previous project. I have even made a test with my previous game and it also shows a black thumbnail despite the fact that it was just fine with 5.0.3.

Is this something that someone else has experienced with 5.0.9. I am a mac user and currently using Mojave, so it's definitely not an OS thing (I was using the same OS with 5.0.3)

Also, I am experiencing the same problem even when I use custom thumbnails from the scene properties menu.

Some help would really be appreciated! Thanks!

A simiar problem was reported some while ago, but i cant find it anymore. 

Any ideas, if there's a custom script solution for this? Is there a possibility to be some other source for this problem other than metal? For example a path issue?

I will try later on to run it on my windows pc to check if there's an issue with it as well.

Quick question: have you typed in a company name &/or game name on the main settings section of the editor? if you have, have you used any special characters or accidentally left whitespace at the end of one of the names? - anyway, if you have typed names in either of them then please try deleting the names, save your project & run it again.

Actually there's a quick test you can do. Are you able to open up the location where the log &/or save game files get saved to via the go to messages.log option thing in the dropdowns under either of the play buttons that are next to the searchbar, or does it mention some error message instead?

The path is like this:

"/Users/myUser/Library/Application Support/Company/GameName//config.ini"

This "//" looks suspicious to me although I'm not sure that it affects the screenshots themselves. Is there a chance that something similar creates the problem?

Device = OGL

But Apple might remove OpenGL or have removed it already.

I have tested with Catallina and the game works just fine. (at least for now )

Also please bear with me for a little bit more but any ideas which tags are not compatible with5.0.3?