Haven't seen it (because I never use the feature), but eBay and Paypal both have been trying to make it harder for sellers to get direct buyer contact info for months. Stricter message filters, less info showing in sales records, etc. They may have done away with the feature.
Yep - me too . . .
After getting a non-payer ignoring all my messages
I have used this find a members details before so what's the problem?
It's officially gone now. They did away with the feature. They don't want buyers and sellers being able to contact each other directly because it potentially drives sales off of eBay.
I tried to look up a buyer's info last month and got the same error OP mentioned in July.