I reallllyyyy think you need to stop checking on them. You provide the food you give them in a water bottle cap correct? Put some of whatever carbohydrates you use into it and check back on them in a week. Before I think I say you say you check them every couple of days so stress could be a big factor.
Also they have to be eating the food otherwise they would not be alive. Like in the thread you created before, they are probably eating it when they feel it is safe to go out and forage. When your checking on them would not be on of those times.
Edited by Pumpkin_Loves_Ants, October 20 2019 - 6:58 AM.
Lasius Neoniger (Around 23ish workers)
Tetramorium Immigran (8 Workers)
Myrmica Queen (Not 100% on species)
Formica Subsericea (No workers)