Clicking on link now ignored by Safari

Just updated Mojave (10.14.6) this morning (security update + Safari update). All of a sudden, clicking on a link in an e-mail message no longer opens that web page in Safari. Control (focus) is transferred from Mail to Safari, but Safari merely shows the last tab that was open before.

(I am able to copy the link from the Mail message, open a new tab in Safari, and then paste the link into that new tab to get to the desired page. But, until this morning, that was all done in one step, by clicking on the link in the message.)

Again, this never happened before this morning's update.

Mark