Walk Through Walls, Jump Into Ceiling Blocks

I have a skyblock map where I have used slabs for railing everywhere, which has worked great except this morning I was running around, then walked right through the slabs and into the void!  Also, there is one room with a low ceiling with solid blocks above, and when I jumped, my head got stuck inside the block (like I was suffocating) until I moved forward with the virtual control pad. This kept happening until at one point I tried to modify the railing with a few solid blocks, then suddenly everything went back to working normal again. Screenshot attached of me standing with my face almost inside the slabs. Hopefully this makes sense. Thank you