Well people can use spies to drop your morale so the provinces swaps to them or swaps to AI or anyone else. People can also use gold to do this. Albeit very expensive in gold terms. A combination can also be used. But if they where 90% then I must admit its a bit weird as using spies they can down morale maximum of 10% on a daily basis. So in that case either gold has been used to do so, or it is a bug.

if morale is on 25% or lower it can and may change to someone else, that can be a AI or a person. If a person uses spies or gold on you to do this, those provinces will change, when they do, to the nearest country. So if hes on the oposite side of the world and china is your neighboor of that province, if it does swap, then it will swap to china.

If you file a bug report, a Game Operator may look into the game and tell you what happened, otherwise they will send it to development to look into it if it is indeed a new bug.

right bottom of screen i the game where you are experiencing the issue click on the pictogram to open up settings. it will expand, you can select display colours of provinces acording to morale, resources etc, there is also a pictogram of a bug. Click on it and the bug message system will open state game number anyways (even though it will be linked for admins), describe what happened, supply additional info, and if you got a vid or screenshots, they may be requested trough main page email later on. Dont expect compensation for this bug as its very random and does not only occur on carriers, it can happen to land troops as well. Explain that you waited for daychange (sometimes they reapear after day change), explain you tried (and do try if you have not done so) to delete %temp% files, internet temp files/cookies, tried different browser and specify which ones.. etc etc but even though not expecting a compensation, do notify them like this. If not then it will never be fixed/discovered cause.

Good luck bro, see yah on the flipside