market place prices disappeared when selling?

I've had that issue before, it's most likely a bug of some sort. It normally went away after reloading the page, at most I had to wait a few minutes (server load maybe?) but you seem to be experiencing a worse variant of that problem. Does it also happens in the browser or only on the client?

I think there is some sort of rate limitation...

Which is pain with larger inventories.

I can confirm this is a thing and has happened to me for the last few years, Every major sale I sell between 2,000 - 5,000 cards, After selling maybe 1,000 the current prices disappear from both the browser and Steam client. But it doesn't stop me selling cards.

After 6 or so hours the prices are back and I can continue until they disappear again.

Just happened again to me two days ago (but in browser). Don't know how to fix it, but you could try using the Economy Enhancer addon as a workaround.

Regularly happening to me, yes. Usually selecting another item and waiting it to load, then reselecting the original works. At worst, an inventory reload tends to fix it.

Its been buggy for me. I view my badge progress, click on a card I'm missing and search the market. After I buy the card I view the badge progress from the new card I just bought, find the next card I'm missing and there is no option to search the market, only trade... I have to keep reloading it from a different page.