This is a technical bug I have discovered while editing worlds via documentation. I have added a behavior pack that fixes the tall grass generation in my survival world, and it should disable my achievements which makes sense. After playing for some days, I tried to re-enable achievements for the n^th time using a third party program called MCCToolChest PE (The game previously disabled achievements even after I re-enable it because I attempted to copy the world. This was done manually.). After re-enabling it, I went to the world settings without joining the world, and the game says achievements are enabled. But when I join the world, the world automatically sets to a rainy weather and my achievements got disabled automatically (not manually!).

I am not sure if this is related to me placing command blocks before the latest re-enabling. I observed that after I placed command blocks that are activated by daylight sensors, in order to temporarily fix the bug about Wandering Traders spawning deep underground, this issue starts to happen and it does not seem intended.

Steps to Reproduce:

1. Generate two worlds in survival with cheats on. 
2. Switch to creative.
3. Have one world with command blocks toggled by daylight sensors, while the other one having none.
4. Quit and save the world, and turn cheats of both worlds off.
5. Follow this guide for each world: https://youtu.be/nvG0O5YKKYs. It shows you how you can re-enable achievements. Please note that it is not necessary to use MCCToolChest PE. Any application that can edit the level.dat and player details without corrupting the files would do.
6. Import back the worlds and go to the world settings of each without joining in the world. Try to tap on the “Cheats” button (which should be off), and you would see that the game pops up a warning stating whether you would want achievements off. Do NOT toggle cheats at this point.
7. Join the worlds, observe the weather, and try to tap on the “Cheats” button again in the world settings screen while being in-game.

Observed Results

The world with command blocks have rainy weather and does not pop up the warning message about achievements in-game when you tap on the “Cheats“ button.

Yet, the world with nothing at all should have clear weather (because the last world save also has sunny weather) and should pop up the warning message in-game.

Expected Results

Both worlds should function the same as the last world saves, except that achievements have been re-enabled. In fact, every world should have sunny weather and warning messages just like the world with nothing at all.

Note

I’m not sure if this happens 100% of the time. Yet, here are some worlds you can try on to reproduce such technical bug.

https://drive.google.com/drive/folders/1BMer5IvPWGmgS-f0rItlYheqLTR8q0ZQ

The one with date 13/3/2022 should work perfectly fine.

The one with date 15/3/2022 would have the issue.

Important Remark

I have NOT edited anything else besides what has been mentioned in the YouTube guide, NOR I have deleted any files in the 15/3/2022 world folder. It worked for a few times at first until today.

Since it worked initially, I can confirm that this is a technical bug instead of an editing mistake.