Thank you! Same problem and yes selecting the secure folder and then the home key b4 login works perfectly ! I didn't have to reboot either ! Both my top dropdown and recent keys were affected. Mine was due to a Samsung auto fill that was trying to auto fill an application (with wrong information) and had to scan bio metrics for authorization. This worked perfectly thank you.
The problem was marked SOLVED by temporary fixed, which I was not satisfy with.
After much searching of solution, I believe I found the actual problem and solution. I do need more evidence as I tried on my phone and I no longer facing this problem AT ALL!!
Goto Settings > Search for Optimise battery usage > Press "optimise battery usage" button > the goal is that you want to make sure your SECURE FOLDER apps is not optimised.
On the top right hand corner search for "secure" and find the SECURE FOLDER apps and make sure it is NOT optimised.
Do note, that the name might change if you change your SECURE FOLDER icon name.
eg. I change my to SECURE FOLDER to a name called "PREMIER", then you have to search for the word "PREMIER" instead of SECURE FOLDER.
I do hope this helped some one.