JOSM “Uploading data for layer x” is still shown even after changeset was automatically closed?

I have made about 9,500+ edits in a layer and I forgot how to efficiently upload in chunks (I recently used "2", instead of for example 1,000, in a previous changeset which took several hours to upload), so I uploaded them in a single changeset using only one request thinking it would be quicker.

The changeset was open for several minutes and was automatically closed after 1 hour. Upon checking on JOSM, the "Uploading data for layer x" dialog is still shown even though the changeset was already closed. To ensure the edits were really uploaded, I checked the changeset at achavi and also at the main OSM page/map, and the changes were indeed uploaded.

The JOSM dialog has been displayed for more than an hour now, and I am quite concerned it might have hanged. Should I safely ignore the message and click "Cancel" or should I wait for the dialog to close by itself and the "Upload successful" message to come out?