I had the same issue. To get rid of it, I checked the applocker files for familiy safety below C:\Windows\System32\AppLocker\
(mine looked something like C:\Windows\System32\AppLocker\MDM\1320142945675408983{F6FD3A45-289F-420B-A951-2A16A5830310}\AppLocker\FamilySafety\FamilySafetyGroup)
The actual applocker files are placed in the subfolders exe and storeapps as text files.
In my applocker files a deny was in place for a Dolby store app (not sure how it got there, I didn't blacklist apps for my children);
This block looked like in the storeapps policy file;
Action="Deny"><Conditions><FilePublisherCondition PublisherName="CN=58D26209-1D57-482C-B403-B655571B5C7B" ProductName="DolbyLaboratories.DolbyAccess" BinaryName="*">
As I don't use this app I just uninstalled it (although I could have probably tried to delete the deny entry from the file / check if it reloads from the family safety settings or something).