Thanks guys, setting up a new connection with a ipv4-only server made a difference but this also led me noticing that the ‘DNS servers’ field was empty in my previous configs. Since the import worked normally for a ipv4 config file, I guess there must be something wrong with parsing config files with both ipv4 and 6.
I’ll try looking around if there’s an existing bug report for this, I noticed that this other one just got fixed.