Time Machine won't backup after upgrade to 10.14.4

here is the response today from an apple care senior advisor, after the latest diagnostic logs were sent to the engineers :-

The Engineers replied today and at least for now we do not have any further troubleshooting steps to perform.

They state that they have received the Logs we sent them and are currently investigating the situation and will put us up to date as soon as they find a resolution.

That being said, as soon as I receive any new information in regards to your case, I will be contacting you.

Hope to speak with you soon.

Best Regards

Fabio Costa 

Hi, I just wanted to updated this chat with what's happened this morning with my iMac.

Every-time I have connected my HDD to carry out a Time Machine back-up since having this issues with FileVault the message that pops up saying that FileVault is doing it's thing has always given a time of about an hour for it to do what ever it thinks it was doing. So today I though I would connect my HDD and leave it and see what it does, however on connecting my HDD I was able to instantly carry out a back up with Time Machine and had no issues with FileVault. Since then I have done two back up's and everything has all worked OK. I have re-started to my iMac and everything is now back to normal, meaning the small red ! mark I get on the Time Machine presences has now gone.

I'll give it a couple of days of normal use and see what happens.

Anybody else now able to carry out a back-up OK?

I have not altered any settings or done anything since carrying out the normal checks.

Good for you. But no change here. Usually, but not always, I get one full backup after a shutdown and normal start. Why the beast sometimes, seemingly at random, does not deliver a full backup after some starts is a mystery to me. And I get no hourly backups. Using an iMac, late 2015 model.

Another new problem: the wallpaper briefly shifts sideways sometimes a few inches then slides back into place. Have not seen this before.

Thanks for the suggestion. I tried it. But it didn't work.

I had one complete backup, then within a minute I tried another, on a separate external drive, but then the usual problem returned: our friendly little red dot with the white "i" in the middle, and clicking on it brought the familiar message, "Time Machine did not back up because FileVault was encrypting or decrypting a disk. Backups will resume once FileVault finishes."

Waiting for Apple or Godot to resolve the situation, bring deliverance.

Soon, I hope.

Same as above. One and done, despite the suggestions. Sounding like a Mojave problem.

Strange; it started working again yesterday for no obvious reason – worked fine all day. Now broken again. I didn't do anything in either case.

warmd at the scene of the crime in my case, too. No change after Safe Mode boot.

ditto here.

Definitely broken, going to other backup solutions I guess.

Has Sage Mode worked for anyone with this problem? Or any of the other suggestions?

I've tried all the ones named above ... and no change.

How can i log the issue with them? I am having this issue too... i think i have the exact same mac as you too.

O frabjous day! Thank you eagle for the notice. I was unaware of any update awaiting downloading. Now it is doing so as I type this. I'm hoping for the best.

TM working in full excellence since the update over 24 hrs. ago. All backups happening as they should be.

👍