When something does not work

What each failure actually means

Every failure below has been seen for real, and each one is here because its symptom pointed somewhere other than its cause.

Reads only. Nothing in SharePoint is changed.

On this page What it tells you How it runs What it will not do Read next

What it tells you

Clicking a placeholder does nothing: Check on the Archive endpoint step (step 3) checks whether the endpoint, the .shurl registration, and SharePoint's cache have the expected actions and icons.
The endpoint answers 404 on every route: it is running but has loaded no code. The wizard's Check now says which of the four possible causes it is.
A location could not be read: the report names it and marks the result incomplete. A short count is never presented as a full one.
The run refuses because the endpoint serves a different storage account than the run would write to: the storage step was re-run and a different account chosen. Files archived in that state would be written where a click cannot read them.
Owner and Contributor on a subscription grant NO access to the data in a storage account. Every provisioning step can report success while every click fails.

A click does nothing. Open Configure tenant and choose Check on the Archive endpoint step (step 3). It reads all three causes. A red bar saying people cannot open archived files means the approval for a click to act as the person clicking is missing: press Repair now. Outdated click actions or icons: choose Repair file type. SharePoint still updating: nothing to repair - check again later, then reopen the library in a new browser window.
The endpoint is not answering. Press Check on the Archive endpoint step (step 3). It asks the endpoint itself and reports which of the four causes applies, rather than leaving a 404 to be guessed at.
Nothing was examined. The report says which locations it could not read and why - a missing library id and an unknown site are different problems with different fixes.
A file was refused. The row says which reason. A hold, a checkout or an already-archived file cannot be archived by any setting; too small or too recent can.
Access denied writing to storage. The signed-in account needs a Storage Blob Data role on the archive account. Owner is not one of them - it is a control-plane role, which permits managing an account without reading what is in it.

There is no way to ask Microsoft how far a file-type registration has propagated. The elapsed time is the only honest indicator, which is why the wizard reports it rather than guessing.