Excel file in a web page "Couldn't load this workbook"

[ellcres11]

I am trying to access a website which I have previously used successfully multiple times a day. It has two embedded Excel files. 

Yesterday, I tried to load the page and got the attached message. I have deleted all temporary files. I have tried in both Chrome and Safari and am using a Mac, on OS Catalina 10.15.6

Downloading the files and using them from my local machine is not an option.

Please help!

[#2]

@ellcres1 I am also having this same issue. I was able to access my file from both the app and on the browser. Today I receive the same error when I attempt to open via the app, however the browser version will open fine.