This occurred to me today as well.
I toggled ransomware protection off and was able to open excel.
Then I ran the support tool from the provided link in the previous message:
https://support.malwarebytes.com/hc/en-us/articles/360039023453-Upload-Malwarebytes-Support-Tool-logs-offline
It did it's thing, updated my malwarebytes, and turned ransomware protection back on.
Scheduled scan tomorrow so we will see if it shuts excel down again.
I do find it odd that one would not be able to select ignore on a particular file for this.
Seems like that would be the easiest temp solution but I'm no programmer.