I updated this ticket with debug data
I have set syncChunkWrites to false now, the Problem is still existing.
See crash-report appended to ticket
I created the report exactly when the chunks disapeared
I can't find this in options.txt, so I added it exactly this way to it:
sync-chunk-writes:true
after loading the world, the game has converted it to:syncChunkWrites:true
As far as I can see, no chunks are missing, but this bug needs some time to appear. But now the game is completely unplayable, because it responses for ca 2 seconds, then freezes for 10 seconds, then is for 2 seconds responsable, then freezes ... and so on.
I try to wait some time, if the bug appears
please watch this video. It's from today with 1.16.pre5 -> the bug is yet present. You can see the version on ~ 1:20 in the video, it takes a very long time after pressing F3 for MC to display the debug infos
https://drive.google.com/file/d/122JOpPtBG_YSEl0SF61FJwwOC-wZisLl/view?usp=sharing
the pictures, I appended, are for documentating reason.
So, now I had the time to check this. And you're right. These command blocks are part of an ore-generator, I built to learn more about command blocks and a bit more complex command block chains.
But here is the one thing, I can't understand. If I am in the overworld, the generator is running for one or two seconds, no lags, everything is fine, but if I am in the nether, it produces such heavy lags. Do you have any idea, why the behavior is so different?
For now I fixed this with a "execute if entity @a[nbt={Dimension:"minecraft:overworld"}] ...." command block.
Thank you for all the support ... and a big sorry for this bug report. Mea culpa!