I'm using ArcGIS Hub for country-specific data. I have 3 gallery items that link to Web Apps, one each for England, Scotland, and Wales.
In Chrome, it usually lists all three. In Firefox, it's only listing the first two. Mobile browsers usually just list the first two. I just checked MS Edge and it is only showing 2 as well.
For reference, here's screenshot from Chrome:
And a screenshot from Firefox:
Not sure what to do with this! Any help is appreciated.
Out of curiosity on your behalf I searched what kinds of Web Apps may not be compatible with certain browsers. What I found does not seem likely since it appears that these are all duplicative in some way with one another - but, any chance one of them is a 3D app?
https://doc.arcgis.com/en/web-appbuilder/latest/create-apps/xt-system-requirements.htm
I am not having this issue with my galleries on mobile, in Chrome, and Edge, but I do not have Firefox to check that particular browser. Sorry if this doesn't resolve it, but just in case there might be something different about the Wales map I wanted to share what I found.