Hi all,
In a flow I have a section that waits for an approval of a certain person. Waiting for this approval, the flow sends an email to someone that contains a button. When the person clicks this button, it opens a link to a certain file that was collected from a certain folder in SharePoint. It has worked thousands of times already.

Now the problem is that suddenly the link to the item changes. It deletes certain underscores from the link, resulting into a 'page not found'.
Example:
file in folder: sharepoint.com/sites/invoices/15154_4_file.pdf
Flow picks this link up under the variable 'Link to item' which should be exactly the same. But when the person clicks the button however, he gets redirected to the next link where the underscores just dissapear:
sharepoint.com/sites/invoices/151544file.pdf
I have made several test and everything keeps working fine. I can't reproduce this problem. However, still a few users experience this issue.
I tried using a static link with the file name as well, but still works fine:

Someone has any clue how this could be, or how I could reproduce the problem? Or is this maybe because of Microsoft Flow itself and I cannot do anything about it (else than sending in a ticket)?
Many thanks!