internaldate parsing error on fastmail

[Peter P. <pet...@fa...>]

Hi,

I am trying to run mbsync on my cell phone under Termux. When trying to
sync a fastmail account I am getting the error
	IMAP error: unable to parse INTERNALDATE format
A possibly related issue has been described here
	https://vxlabs.com/2021/03/21/mbsync-copyarrivaldate-yes/
but I have set CopyArrivalDate to yes.

What can I try next? Thank you!
Peter