SUMMARY
DigiKam seems to sort standard by filename. When I open a folder with items from different camera's it starts for example with DSCF3079.jpg, DSCF3080.jpg, DSCF3081.jpg and then P1020205.jpg, P1020206.jpg, P1020207.jpg and so on.
Then I sort the items on filedate, thats oké. But when I want to change the order of a few items for example because they have the same topic, by dragging them, I must change the order in 'Manually', only then I can change the order by dragging. Here is the problem: when I change to Manually all items are sorted again by filename! I wish they should remain in orde by filedate. Now I need to sort most items manually by filedate.
Hopefully i made my point clear.  

STEPS TO REPRODUCE
1. Sort by filedate;
2. Sort Manually.
3. 

OBSERVED RESULT
When sorting Manually they don't stay sorted by filename.

EXPECTED RESULT
I expected they stayed sorted on filedate bacause I prefer that, but sometimes I want to have a few items in a folder by exeption not sorted on filedate but on topic.

SOFTWARE/OS VERSIONS
Windows: 10
 

ADDITIONAL INFORMATION