The newly released update of SS6Pro to 22.214.171.124 has fixed the Date&Time picker for my iPadPro iOS14.4.2, which has the display settings of Light or Dark Mode.
The issue still remains on my old 2nd gen iPad with iOS 9.3.6. This iPad & iOS doesn’t have a Light or Dark Mode display setting.
Checked an iPad Mini iOS 12.5.2 with SS6Pro 126.96.36.199 and it too has the Date &Time picker that is not visible. It appears that this bug is only present in iOS prior to iOS 13 when Dark mode was first introduced.