APN cannot be edited with eSim

I’ve used eSim’s already for many years on my Fairphone 4 during holidays abroad. This year in Japan I installed the Airalo eSim but was not able to get it working, even with the support of Airalo.

It turns out that it is not possible anymore to add an APN anymore. You can click on the + but when clicking on Save it does not add it. Therefore I can’t get the data working.

Any ideas how to solve this?

I’ve noticed that my own carrier no longer allows APN editing. It would be interesting to get some info from the industry on the subject. I suspect the choice lies with the carrier.