Audiogon has NEVER worked for my Macs. Multiple macs, multiple OS versions, all available browsers, from 2003 when I first tried (and paid!!) onward.
They NEVER answer my support emails.
Instead, I don't pay them to buy and sell, I pay eBay. IMO they totally suck. And, sure, I totally get that things break, that site dev is expensive and for a period a group can't support every platform/browser. But it's been almost a decade. It's never, ever worked for things like posting, logging in properly, etc. Only the free stuff works on my Macs.