I've had the same issues with having to use the 'Update' button, then having to access my bank feed by entering my First Direct password and key-pad generated number. It first happened around the 4/5th March, but I resolved it eventually by disconnecting, and then re-connection the 2 FD accounts I had linked to QB.
The QB help 'chat' mentioned 'Open Banking' issues with FD being a probable cause, but FD are fully compliant with this as far as I know...The same thing has just happened again today (3rd April), and despite clearing my cache, the 'Update' button just gives the message to 'try again tomorrow'......
Getting v.frustrated. :(
