I think, they didn't sample actively there. (That's what I read.) If someone shared samples with the WIV, this would have probably become known by now.
My problem is really with building evidence by "unknown unknowns": we don't know neither object, nor subject, nor circumstances, but, if we ignore all we do know, this is clear evidence. (Hum.)
Who knows what they sampled but haven't released - the WIV took down their virus sequence database in November 2019 and it has not been shared since.