OK - I was able to re-create this, and now its gone away. (apparently for good).

Here's what I did.

When the problem occurred, I had filters turned off (the check box blank). Then I turned filters turned on (the check box ticked), but had no filter chosen (the unamed blank entry at the top of the list), and the program started correctly positioning to the edited Vendor.

I cannot get it to fail any longer, even with a machine reboot.

Thanks for the solution Andrew. I think I can narrow this down further. If you deselect the filter while still having a filter selected (non-blank filter name) the problem occurs. Setting the filter name to blank firts prevents the problem from occurring.

When I open the Vendor List screen - Filters are unchecked and no styles are set.
I scroll down, double click on a vendor to edit.
Click OK.
The venodr that is now highlighted is the top one.
When a new vendor is created - it is the same. When you click OK it bounces back to the top of the vendor list.
This is consistent every time - and only since the AP upgrade.
DIC is clean
But I do see that when the three sample filters that came with the upgrade are deleted - the results are "normal"
So - if there are filters in place but not in use it will rise back to the top.
And now the question is - why is this not happening in AR.

Turning filters on, but having NO filter selected fixes the problem permanently it seems. Please try the steps again. There's likely an uninitialized variable in the AP grid which isn't in the AR grid (which shipped later).