I’m going to go out on a limb and make some assumptions.
I’m assuming you know about stability and pillars and those methods do not account for this issue.
But when you tried the same build configuration on a live server, was it in the exact same spot?
I only ask because I noticed during my time playing the very ground you build on could sometimes effect stability.
My suggestion is try the same configuration at a different location in your SP game.
If the ceiling tile will place at a different locale, then moving the initial build with the issue might rectify the problem.
As a disclaimer I should mention I haven’t played in quite some time, and the similar issue I had only occurred in one area. It was over by Sepermaru between the city and the green wall.
I don’t know if this is even still a thing, but there is what information I had, should you choose to test this thing out.
Tried it all over. Just a one tile box for the journey step, went into creative - still nothing. Will not place to foundation (stability not an issue) or wall. tried every tile, every foundation and every wall in creative - nothing.
Settings are all barbaric, nothing changed in other settings.
I would do private, but I hate Monty Hall stuff. Official is full of T1 trash and PvP try hards (5 guys storming the new solo who just got to Noob River), so I am Billy Idoling for a while until something looks decent again.
Looks like it might have been something with the barbaric settings, or something I did, because did it on the first setting and was able to place a ceiling.
Thank you for your patience, do you need to close this or can I?