I just updated to 25.7 and was working to migrate from KEA DHCP to DNSMASQ. I exported all the KEA records and put them in the same format as a dummy record I created and exported from the DNSMASQ hosts list.
I also tried just exporting a record, deleting it, applying, and then importing that record it had just exported. It does nothing after selecting a file.
There are no options to import. I have tried on the most recent versions of chrome and edge.
It wasn't until I tried clicking the checkbox that it imported. This is a confusing GUI element that needs a label of some kind to help the user progress to the next step of actually importing.