I have a site running joomla 4.0.3 and JCE editor 2.9.14 and I have encountered a problem with my subforms using (JCE File Browser). If I create a new item in a media subfield the buttons INSERT and CANCEL are missing. The only visible button is REFRESH. The strange thing is that if I save the article with this empty item and then open the media field again, all buttons are there and I can add a new image. The same is true for articles that already have saved images in a subfield. If I open one of those all buttons are visible.
I have tested the native MEDIA subform and using that I don't experience these problems so as far as I can tell it has something to do with the JCE File Browser.
The site have been upgraded from joomla 3.9.10 to joomla 4.0.