I’ve been experiencing all the things expressed here, and in other similar posts, so I contacted Mega support (I had just purchased a PRO I subscription for use with Duplicati, and so not happy). Their response was:
Hello,
thank you for your email.
Your issue does not seem to be related with MEGA, since from MEGAsync is working fine.
The issue could be cause by the use of this third party software.
We do not recommend any third-party tools.
Please note that these tools are insecure and do not fully implement our cryptographic protocols, therefore if you cannot access your account, or that third party tool did not work as expected, that could be the reason.
If it is the case, you must use one of our official tools (MEGAsync, MEGAcmd, mobile apps or MEGA in browser) to unlock your account, and stop using this third party tools software.
You will have to wait 30 minutes after log in for your account to be unblocked.You can also exit it by going to your MEGA account session history and click “LOGOUT” on those “Unknown”/“Linux” sessions.
MEGAOur onsite download is already using multichannel downloading. Any other third party download client have not been approved or authorized by MEGA and should only be used at your own risk, and we do not give support for that tools.
Also, these foreign tools cannot detect your quota and could limit your bandwidth.
To manage your transfers, the best way is to use MEGAsync - our desktop sync and download/upload client. It can be download here: MEGA
From MEGAsync interface, click the gear icon at the top-right corner and select “Import links” from the dropped-down list.
Kind Regards,
MEGA Support
Indeed, when I checked my Session History I had many, many, ‘unknown’ sessions. My (personal) assessment is that Mega no longer works well with Duplicati, so I’m off to Google Drive or B2 (where my benchmark tests give a few seconds for a test full backup of 200Mb, versus 4 hours plus on Mega!). Mega’s loss…
Hope this helps others…