This happened to me with Folder Lock twice, the only way I found round it was to uninstall and reinstall it. I enentually discarded it as it was not reliable in favour of Hide Folders XP2 which is excellent.
OnePlus 5 review
Alice Saey's mesmerising animation for Dutch singer Mark Lotterman
iPad Pro 10.5in (2017) review
Comment booster votre iPhone ?