DigiKam photo ordereing

I am finding, in some circumstances (I wish I knew the cause!) that the addition of ‘by manual and’ to the item sort order results in chaos - it seems to have some ‘memory’ of a previous ordering and I can find no way of clearing it.

I tried re-naming and then sort ‘by name’ - the photos appear in the expected order - but as soon as a chose item sort ‘by manual and name’ they revert to some order I can’t explain nor can I find a way to clear whatever is controlling this order.

I found one post online suggesting that a database correction was possible using an external database to reset the ‘manual column’. Surely this should not be necessary?

Has anyone found a solution - or can the program authors create a solution?