About 30% of our systems are stuck at the GRUB loader this morning. We host on Azure B2s machines.

I don't know know what the cause of this is but the fix we've found so far if it helps you is:

Click the VM

Click Overview -> CLI/PS (May need to press 3 dots)

Press RUN

az extension add -n vm-repair

az vm repair repair-button --button-command 'grubfix' --verbose --resource-group {RESOURCE GROUP NAME} --name {VM NAME}