The detail bug as screenshot by Rocket J Squirrel.
It is wise to rollback to previous version without affecting the data?
THE BLACK LINE IS APPARENTLY THE DROPDOWN LIST, just not expanded.
Will report as problem, but wanted to leave one more note here. I have Quicken 28.18 on 2 different Win10 machines. Only one is showing this problem. This bug has apparently been around a long while; it was reported as far back as Q2009; see: https://community.quicken.com/discussion/7083014/security-detail-view-stuck
A re-install may help? Will let you all know.
UPDATE: On my computer having this problem, I did a full un-install and re-install of R28.18. The problem remains. While both my computers are Windows 10 Pro, the one with this Quicken bug was an in-place upgrade to Win10 from Win7 (their free upgrade back when they offered it). I am betting this bug has to do with configuration of installed libraries -- like Microsoft "Visual C++",
DOT-NET (.NET), or perhaps a Quicken-authored DLL.
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