Some Drop-Downs not saving previous selection position

Mojave 10.14.6 / LO

In the attached Document there are two drop-down lists, marked with pink background colour.
The bottom drop-down “remembers” the previous number selected, meaning when I enter the list the previous selection is highlighted in the list. Therefore all I have to do is select the next one down after the highlighted selection in order to progress to the next selection, which is exactly the behaviour I want.

The top list, however, seems to remember the first 4 selections, but when I get to the fifth, it “forgets” the position it was in i.e. nothing is highlighted, as if the list has “reset”. So, to progress to the next selection, I have to look at what characters are present in the cell and scroll down through the list to get to the number after it, which is a bit inconvenient. It also presents the possibility of a student skipping selections by mistake, as there is nothing in the list to guide them. Finally they can’t simply use the keyboard to navigate to the next selection with the key sequence Option+down arrow > Down arrow > Return, as selections have reset from the top of the list.

I’m not sure why the behaviour is inconsistent when both drop-downs get their data from the same source, and both are single, unmerged cells… any tips?

Inconsistent Drop-Down list Example.ods

Please , announce your LO and OS Version.


My mistake; have amended