Problem mysteriously resolved itself last friday 23rd after I managed to get the issue escalated to ebays technical team. No response from ebay admitting there was any issue, and no notification that it had been rectified, but they obviously managed to find and fix whatever was wrong.

A lot of customers were frustrated being chased for messages they kept telling me they'd sent repeatedly, yet I couldn't see them at all.

At least it finally got fixed.

It would have been handled better if ebay were to:

A. acknowledge there was an issue (which they didn't)

B. advise us when they fixed the issue (which they still haven't).

As an e-commerce seller choosing to use ebay as a selling platform (and spending lots of $$ on ebay fees each month) this lack of transparency when they have an issue is very disappointing.