FG621-EA modem firmware download version 16121.1034.00.01.01.10 fails

In winbox I get the message on my LTE router that there is a modem firmware update. When I check the update status:

/interface lte firmware-upgrade lte1
installed: 16121.1034.00.01.01.09
latest: 16121.1034.00.01.01.10
status: update available

However when I start the update I get a download failed respons. Equally so when I try to download it manually. However the previous (current) firmware file can be downloaded:

/tool fetch https://upgrade.mikrotik.com/firmware/FG621-EA/16121.1034.00.01.01.10/image
status: failed
code: 404
downloaded: 0KiB
failure: Status 404, Not Found

But downloading the current version does work:

/file> /tool fetch https://upgrade.mikrotik.com/firmware/FG621-EA/16121.1034.00.01.01.09/image
status: finished
code: 200
downloaded: 1641KiB
total: 1641KiB
duration: 2s

How can this be solved?

BTW the reason why I think a firmware upgrade might be useful is because I get regular AT-respons errors

HW is LTAP-2HnD, ROS is 7.23.2