Just to update, I turned off the incubator today, day 25. Eggs had no movement and one had a horrific smell. I opened the eggs up carefully from the air cell side just in case, and all chicks were gone to heaven

6 were well developed, had their baby downy feathers, some dark colours, some light. None had pipped the inner membrane and the yolks had not been absorbed. Membranes were not dried out, I just don’t know what happened. So sad seeing perfect little chicks gone with no apparent reason. Incubator seemed to have done its job but we didn’t make the final hurdle.
Gonna count ourselves lucky we have our one little chick. We only did this because we had planned on getting chickens (totally new to us!) and I thought it would be even better if we hatched them ourselves. At least we had the experience with one precious little baby and I’m collecting 3 more tomorrow from the breeder. Cannot wait!!!!