GodRosen

I am able to replicate the same issue with the (I hope I attached it right) Lockable chests add-on. The item in game is called Recognition Module and it has a stack size of one.

If I click to pull a stack out of creative the entire stack disappears. (max stack size is 1) if I have 2 item slots for this item then shift click them from the hot bar into the inventory they will stack and 1 of them will get voided. 

If I did not attach the file correctly please see this link for the add-on. 
https://mcpedl.com/lockable-chests-addon-1/

If you have any questions or comments please feel free to hit me up and AvgZing will probably ping me in Discord. lol

Thank you

I can confirm that this is an issue. But mine happens daily. Also it's not commandblockoutput it's all of them. 

I was having issues with the difficulty, keepinventory, randomtickspeed, firetick, tntexplodes, bedexplodes, and probably more that I have forgotten.

To resolve the issue I downloaded the world went to the world settings (not logging into the world) and set the gamerules and re-uploaded the world to the realm.

I left commandblockoutput on true and I have an add-on that automatically changes it to false. Everyday or at least nearly everyday I can tell that the gamerules reset when my command blocks trigger in chat before the add-on changes the gamerule.

I also had a realm add-ons issue where I uploaded my add-on and all the versions of it where I was working on it and updating it incrementally and tinkering with a single setting at a time back and forth all uploaded onto the realm at once instead of just the one selected version of the pack. Then when I tried to remove all the different versions of the same pack and keep the one version I wanted to keep on the realm I got an error when I tried to log on that read "Some of the selected content could no be applied"

To resolve this issue I had to go to the storage setting off of the main menu settings button and delete all but the one version of the pack I wanted installed.

(and to clarify when I upload a different version of the same pack I am getting different and separate entries under the packs to install onto a map or realm for each individual version of the pack like each version is its own pack. I suspect I am doing something wrong to end up with this behavior but wanted to explain this to clarify how my experiences can be slightly different from how Savage's experience was)

I make addons and nothing works for me when trying to import an add on. 1.13 and 1.14 bedrock edition has affected me trying to import addons. I use .McPack file extension and the game opens or if it is already open it'll switch windows to the Minecraft app but it will fail to produce a successfully imported message and I am unable to see the added addon in the storage part in the settings. I operate off of windows 10.

I will also add that it is slow to boot up. Will have to desktop icon several times before it finally opens. While online and while offline it takes a while to load. While offline only do I see the Launching the Game Failed screen.