Hi, I have the same issue. Don't use my yahoo account much, but when I checked it my problem is the same. I tried to connect on my android phone as well and it said it couldn't connect, although a recent email appeared in the inbox. But I can't send from it. Two step verification is disabled and use of less secure apps is permitted.

Here we were discussing the Operamail desktop, in your Android phone you have to use the official and updated Yahoo app.