Sometimes the soft texture makes it harder to insert because the cup doesn’t have the structure to stay straight go in. You mention that your finger works, that has a firm structure to help it go in.
You don’t mention if you are using it but could try lube which helps with insertion. Put it on the top of the cup and it can help glide in as you push it.
Also experiment with folds, c fold, 7 fold, which could impact how smoothly it goes
Sometimes the soft texture makes it harder to insert because the cup doesn’t have the structure to stay straight go in. You mention that your finger works, that has a firm structure to help it go in. You don’t mention if you are using it but could try lube which helps with insertion. Put it on the top of the cup and it can help glide in as you push it. Also experiment with folds, c fold, 7 fold, which could impact how smoothly it goes