One of my players was trying to add studded leather to their inventory, but the window to select inventiory or backpack does not pop up and the item will not add.  I confirmed this on several of my characters as well, so did two of my other players

Having the same issue (although it works on my phone).

I can delete items from the inventory window, the equip or unequip button works, and the quantity buttons work.  I can not add any items into the inventory NOR change the location of any items currently in the inventory from "equipment" to backpacks, bags, bags of holding, component pouches, or ammunition containers.  Just in case it is helpful for the bug hunters I use Firefox as my browser.

Still not functioning.

Everything works for me in Firefox 142.0.1. Anyone having this issue should be posting what browser they're on.

I am also using Firefox 142.0.1 and it is still not working.  Odd...

Well...  Firefox works while in troubleshoot mode.  I have exactly one extension running.  It is Above VTT.  I uninstalled Above VTT and reinstalled it to be sure I have a clean copy.  When Above VTT is active the character sheet does not work (as above), when Above VTT is disabled it works as intended.  Thank you for your direction on troubleshooting this Spamandtuna!  I might try a total Firefox uninstall/reinstall tomorrow when I have time.

I don't ave any extentions enabled or intalled.

Yes multiple people in the party have the issue, we tried chrome, firefox, ios. the button worked on phones and ipads, but not web browsers.