You may want to check out this link. It's interesting that you only experience the issue with the one piece of custom content; but I hope this is still helpful!
I have the same issue; I believe it is due to UI scaling. When I scaled the UI back to default, it fixed the problem for me. It seems like the tabs aren't made to scale at the moment. I just try to ignore it. Hopefully they will fix it soon!
From: "Culling, Relationship Culling & Decay: Current Status" https://forums.thesims.com/en_US/discussion/comment/15366827/#Comment_15366827 In my experience, I found three tombstones on a park lot in the snow (the Sims froze to death). I had visited the park a couple times but did not witness the deaths of the Sims (I…