I have the same problem with an Intel NUC6i5SYK and a Pair of U2417H's using MST.
Second Computer using HDMI on both monitors has no problems with blinking.
Yep, I've been getting the same thing.
After this, I noticed on Facebook that I had an alert to accept the login. But when I did, it told me already done.
Words is left in the security warning.
This started a couple of days ago.