@Galaxy_2Alex how do I mark this issue closed or resolved?
I have been able to resolve the symptoms of this issue by blowing up tnt by the invisible blocks. The explosion seems to reset the state of the block and resolve the issue. But this is still annoying and would be nice to see resolved. Furthermore, it looks like new invisible blocks seem to be showing up from time to time, but at a pretty low rate.
Added a video file with F3 menu on. Video shows a region where I had long ago (~2 years) excavated some dirt down 2 spaces. I was filling this when I ran into the problem again with a few blocks in the first level. I ran into no such issues with the level above this though. It seems like this issue arises in the first block level on floors that I've excavated or built long ago. This world used to be hosted on a friend's personal server and was just recently uploaded to a Realms space I think around 2019 ish. Not sure if this info helps, but I hope it does. Also I can provide higher quality videos if needed. Also added a screenshot of my internet service at the time this video was captured.
No. No lag in game. No unusual lag in booting up the realm either. My internet is stable and typical 100 up/down as well.
@galaxy_2alex I've attached a new screenshot with the F3 Debug menu enabled. Thanks!
@Timothy Phan since there's been some activity on here recently, just wanted to come back and update that I've still had this issue all the way up through 1.16.5. I've transitioned to running my world on a personal PaperMC server implemented on docker and ubuntu. I think paper was able to resolve some of the glitching blocks on first loading, but I've still run into many that I've only been able to resolve with the TNT trick I mentioned in earlier comments.
I may try to create an updated bug report with all of this new information soon. 1 other thing I wanted to try was to use World Edit to take the existing structures I care about from my old world and place them in a newly generated map seed to see if that might resolve the issue. But that will probably be 6+ weeks away until I can implement due to work and travel constraints. But I'll try to keep folks posted if I make any progress.