Jumping through the block/slabs in 2 high gap

Currently not sure what can cause this bug. I'm making a bridge with 2 high gap using slabs, when suddenly the upper block/slabs seems to act like an air block which i can jump through. However when I try to break the block/slabs it's still possible to break. I also tried to make same gap using normal block which it's still giving the same result, I didn't get a record for the normal block, bcs suddenly my game crashed. The world had never been in a creative or having a such add-on. I only use custom texture pack on global resources, which it's should not to be the case for causing this bug(I've included the texture pack that it used for the block texture). *Lemme know if there was a same issues, I've been looking for it and didn't found anything.... *If the video can't be play pls use this link:  https://www.dropbox.com/s/ue2ep9bahqxlbsw/Record_2020-12-16-01-15-30_5c8300b655012b1930f2e0a7b81bf6a9.mp4?dl=0