Activity saved with wrong date, can't sync

[Pandametal]

I did an activity on October 12 but it seems my watch had an issue saving it, and it displays wrongly at January 1st in the logbook. As a result this activity won’t sync with the suunto app, even if it appears on the correct order here. I recorded a fake activity right after which syncs well, it’s just the previous activity that the app seems to completely ignore.
I tried unpairing my watch from my phone, reinstalling the app to force a complete sync… Is this activity lost forever ? I see no way of editing the metadata on the watch