Hi Rudi,
It's a Mendix platform bug. This issue will be fixed in the next Mendix release, I believe.
I had the same problem in a basic app I built (without widgets). It shows the same error on iOS as you described above. On Android it works fine.
Used an old version with a different name of the application in mendix. Build a test .ipa with phonegap. No error and when pressed on the image enlarge like it should. So something changed in my mendix project. I don't know how to find this change tough.
I do have exactly the same error. It looks like it happens on pages with a listview. It does not always popup, but when it does most of the time an icon is missing. I'm using Fontawesome 5 icons in the listview with HTML snippets.
Didn't find a solution so far.
@Robert: do you know if there is a supportticket for this? And maybe a possible work around?