Thanks very much for your post about this, @heavylaw - sorry to hear you've had trouble unlocking these two achievements.
Can you tell me which two achievements these are? It'd also be very useful to have screenshots showing that you've met the criteria for them (so, an in-game screenshot), and then another one showing that the challenge is still locked.
Sometimes, achievements don't unlock if something is interfering with your connection to the Ubisoft Connect servers (but not so badly that you are forced entirely offline). As such, please check our connectivity troubleshooting. In particular, please make sure to power cycle your PC, reset your network hardware, make sure Windows is fully updated, and make sure you don't have any software blocking your connection.
If the issue persists after those steps, please let me know, alongside those screenshots I've mentioned above, and I'll be happy to assist further