I know sometimes that has happened to me in the past, dulling in denting. Especially during the winter months, I’m in Chicago. I’m a big fan of big humidifier. Lol. Did you seen both eye caps in the shed. I know sometimes it’s hard to unroll the shed to check, sometimes I put a couple drops of water on the shed to help unroll it, like lightly moisting it. Hope I’m helping.
I've seen suggestions of extra spraying to get the humidity high for a while just in case it's slightly dehydrated...
It maybe worth soaking a rough textured towel / cloth and letting the snake slither through the towel whilst you apply very GENTLE pressure to the head / eye region ..
If it IS simply a retained eye cap which is indeed possible then it will probably come off gently on the towel ..as long as you give it some time in the towel applying the pressure..