I had a very simple case of two dropdown controls in which the contents of the bottom one (“pick related option”) depend on the top one (“pick master option”) - master option determines the related option list.
This warning appears when I select an option, let’s say “1”, from the bottom dropdown and then select another master option from the top dropdown that causes the bottom one to change its options in such a way that option “1” is no longer available.
Strangely enough, the warning message is a bit misleading there, because in my project here, I found that I had to rename
SelectedValue the other way around.
“the name of the DataSource property has to come first in alphabetical order with the name of the SelectedValue / SelectedValues property”
I resolved the warning by renaming SelectedValue property as to come first in alphabetical order, before the name of the DataSource property.
I’ve struggled with this and I thought to leave this here, maybe it would help anyone else.