Trade Site: Failed to load search state. The search is no longer valid.

I've been trying a few different price checking tools and many times I get the red/white error box at the bottom:

"Failed to load search state. The search is no longer valid."

It appears to be random, not related to 'spamming' searches, just some things return that result ALL the time. Quite frustrating. Known issue? Workaround? Being fixed?