[NEEDS INPUT] Can't place certain objects on platforms

[moriiSola]

I have the same issue, but on a PC - I cannot place objects on platforms unless the floor height of the entire room is the same - the objects will place along the platform edge or not at all. This often coincides with platforms turning see-through/disappearing when viewed from certain angles
My first guess was that this is an EA issue rather than anything else, because I recently upgraded the computer I play from an everyday-use laptop to a brand-new gaming laptop from Acer's Predator series, and the issue followed my redownloaded game from one computer to the other. However, it only appears in certain save files, and if I save my WIP to the gallery and then redownload it into a different save from there, that seems to temporarily resolve the issue? Not sure why though.
(I do play with mods sometimes, but have had them disabled/taken out of my Sims folder when this started occurring. Mixed results there)

[quiescence90]

I built a bar that had a platform with a piano, mic, and guitar on it. I playtested it a few times, changed the lot type to a lounge so entertainer sims would show up, and they used all the objects as intended. Today I found out that sims cannot route to those objects anymore. After some adjustment, the mic and guitar was usable again. But the piano cannot be used even when it was the only object left on the platform. My solution for now is to just remove the piano. But I hope to see this issue fixed.

[oneoldriver]

I figured out a work around. Place a new floor pattern on any space in the glitching platform. You may have to adjust your camera to be able to do so. Once you've placed the floor pattern, click and drag the floor pattern out one tile at a time until the entire platform is covered again. It'll be reestablished as its own 'room', and you'll be able to place the original floor pattern as well as objects on the platform again. Routing is also fixed.

[mangachick14]

I have the same exact issue on PC as moriisola, furniture snaps to the border of the platform and I can't place anything. The workaround I've found is fencing around the platform so that it's a room, then lowering it to match the rest of the floor. Then, I place everything where I want to put it and I can raise it back up again. I notice that it seems to happen more with higher platforms (for example, I was building a stage for a nightclub and the glitch occurred there). Hope this gets fixed soon, it's kind of important that we're able to place things on platforms--like it's the basic function.