Altars are very tricky. Allowing them to be moved has some interesting issues that won’t fix underlying issues causing them to poof when upgraded.

What I think should be done is when you initially place an altar, you can toggle the limits of its highest upgrade so that you know where the final product is going to end up. These final limits are also a hard limit of where you can place the initial altar.

This would make placing an altar a bit more of a pain in the butt, but it will alleviate problems later.

I also wouldn’t say no to non-functioning cosmetic versions of the Altars being available that are just normal placeables and don’t have any weird restrictions.