P: Custom Order lost with slight accidental movement of thumbnail in filmstrip

Do I have this workflow correct?

1. Select Album with a custom sort order
2. Select Three images to perform a Photo Merge - HDR (or is this a Send to Photoshop for HDR?)

Result: 

With Wacom - Sort Order Changes
Without Wacom - Sort Order is stable

Exactly!

Leads one to surmise that Adobe are only interested in focusing their efforts where a financial return is expected (not considering that consequences of losing customers will be the result of their neglect in this respect !!)

What is mystifying is the inconsistency - the sort order can be maintained for several callouts to Photoshop, and then randomly scramble for a few callouts, and then behave.  Haven't used a mouse for nearly a decade so am reluctant to start due to this inconvenience.  I do wish Adobe would take it's customers seriously

Come on!  Lightroom has been unable to remember a previous sort order since version 3!  I routinely have to reset the sort order after importing, switching modes, and using exernal editors.  This is nothing new, and nothing that Adobe has ever bothered to fix.

OK.  I have this problem regularly.  Based on the last few posts I tested (data points = 1) with and without Wacom Intuos 4 tablet.  With the single test the sort order changes when using the Wacom tablet.  When I turn off the tablet and perform the same operation the sort order does not change.  The specific operation I tested is HDR merge 3 images.  Although I didn't test it here, this problem occurs when going to and from PS.

eureka! I currently use a cintiq, previously a wacom tablet... so this all seems to align.  Now perhaps a solution?

Interesting - it could be that Wacom software is contributing to the problem.  I don't have/use a mouse, so cannot compare, although the intermittent nature is becoming more frequent in my situation.  For Adobe not to take note of these problems, whether Wacom contributes or not, is a very frustrating and long standing irritation and hinderance to workflow 

Welp! This thread is 2 years old and it came first in my Google search on this issue. Apparently, it hasn't been resolved. Although I am running an older version of LR Classic. I noticed the issue when using my pen and tablet. It would happen almost every time. When I switched back to mouse it went it never happened. In my case, there seems to be a bug with my drawing tablet. Very strange! 

This has been happening to me since lightroom went CC, i.e., ,about 2 years. In my case the order gets changed to custom absolutely every time I round trip to an external editor (any editor, not just PS).  And it doesn't matter if I start the process from within a folder or a collection. Incredibly frustrating, especially since I am I neat freak and reorder the photos each time this happens.