“With interactive brokers you get a notification after the name of the company that those shares have been lent and until when.”
I can see them doing that if you’re signed up for “fully paid lending” but if you’re not signed up they might loan them out and not ever inform you while they take all the interest. With Ameritrade I don’t have a clue what they have lent out even though I’m signed up for FPL. E*trade sends me notifications daily. I don’t know how IB does it but its got to be better than Ameritrade.
They loaned out some compensation shares I placed with them years ago and then wouldn't let me trade them. We had to have the transfer agent demand their return. Trust me I know you have no control over whether the shares are loaned or not. There is nothing in the system to prohibit this sort of activity.