Have you filed a support ticket for this? And what version of Tableau are you working with?
Thanks for your feedback. No, I haven't filed a support ticket, YET! I figured that I might have caused this problem myself, something related to my extremely burdensome extract, but being esoteric as it is, maybe a support ticket is the best next move. We just updated to 10.5.1.
Were you able to resolve your issue? I am also facing the same issue. I have 2 extracts connected to same Sharepoint list data source. One is running fine but other one is failing with same error you mentioned.