I upgraded to 2.55.2 yesterday which all apeared to go well after a couple of permission changes, but I went to upload some media to a survey and kcfinder displays nothing and gives no error.

Anyone got ideas on how to track down this issue?
A permission to check?

Microsoft Edge?
Did you try with another web browser, like Firefox or Chrome?

I tried with Firefox with the same result, currently using winscp as a workaround. Not ideal

maybe it's related to this:
www.limesurvey.org/forum/installation-a-...07613-unable-to-edit

you can try to apply the patch.

Problem solved with subsequent security update. Not sure if I simply did the update badly previously or the latest update fixed it but the problem is now resolved.