Why does my Onedrive.exe file disappear from the %appdata%\local\microsoft\onedrive folder?

You may be right, but I like to reproduce EXACTLY the scenario that fails.  For all we know, it's not the OneDrive installer exec that MalwareBytes is blocking but some other accompanying process/action.

I am able to manually exec the OneDrive installer, so why isn't MalwareBytes messing with that manual action too?

Just to add "fuel to the fire", this morning I realized that, "oh yeah, I'm not running malwarebytes" on a laptop and it has not had this issue.. That said, I only use it occasionally but boot it up every 10-14 days to update it..

I followed the instructions on BAE4152000 July 1, 2018 (THANK YOU!!!!) and was able to get my OneDrive back working, and put the .exe shortcut on my desktop, as I'm not totally convinced that problems are over.

However, I'm thinking that there is more to this whole thing, as I still can't install the Feature Update 1803 on any of my three devices (desktop, laptop, Surface Pro 2, all running Malwarebytes Premium, btw.)   I wish I'd kept track of all the error codes there, the last one being 0x80244018. I'm now trying the upgrade assistant.  I'm wondering if MS is thinking those of us with Win7 or Win 8 computers upgraded to Win10 are now more trouble than they are worth to keep updated. Just thinking!

I followed the instructions on BAE4152000 July 1, 2018 (THANK YOU!!!!) and was able to get my OneDrive back working, and put the .exe shortcut on my desktop, as I'm not totally convinced that problems are over.

However, I'm thinking that there is more to this whole thing, as I still can't install the Feature Update 1803 on any of my three devices (desktop, laptop, Surface Pro 2, all running Malwarebytes Premium, btw.)   I wish I'd kept track of all the error codes there, the last one being 0x80244018. I'm now trying the upgrade assistant.  I'm wondering if MS is thinking those of us with Win7 or Win 8 computers upgraded to Win10 are now more trouble than they are worth to keep updated. Just thinking!

I have MalwareBytes Premium on all computers and have no issues installing the Windows updates, only the OneDrive issue is happening.

Lucky you! My sister has two devices that are approximately 4-5 years old. Same problem there. No dice updating.

I am puzzled by one thing.

If Malwarebytes is the culprit, why do I have no issue for several days and then it suddenly happens again?

It is not coinciding with a Malwarebytes scan and there is nothing in the logs. 

That doesn't mean it isn't to do with Malwarebytes, but the connection is not clear.