2 of mine are still stuck from months ago , I had 4 lads pulling on them but didn't budge
What seems to get them stuck together is mostly very fine particles of tiles grit.
I've found pulling alone don't normally work as you need to twist them in opposite directions and if need be pull at the same time... Hence why the use of rubber gloves for extra grip when trying to twist and pull them apart.
Obviously it's is important to check and clean them if required first before putting sections together. You will soon know if any grit is still present when slotting together as will make a very slight grating noise. In my case I ignored it and after finishing the job could not separate them onsite. lol