Version 0.9.37c
Reproduced fault 24/11/2018:

1. Reset Profile or Delete Neuron.lua file settings file under your WTF folder in the WoW directory.
2. Pick a Druid (I tested with a level 120) and you should have the 2 default created Action Bars
3. Select Moonkin (Caster) Specialization.
4. Edit Action Bar 1 > Bar State > Select Shapeshift.
5. Edit Action Bar 2 > Bar State > Select Alt.
6. Put Prowl on Action Bar 1, while you are in Cat Form.
7. Put Moonkin Form, Travel Form, Cat Form on Action Bar 2
8. Hold Alt Down, Place Regrowth on the same button as Travel Form, when you don't press Alt.
9. Release Alt and Click on Prowl
10. Click on Prowl again and you are now visible however not buttons on Actions Bar 2 work.

In addition unless you move spells to another button or drag-drop them onto the same button they won't work, Hold Alt and clicking Regrowth works but then Action Bar 1 stops working - system gets into a very strange state. Action Bar 2 stops working.

I would guess that the Bar's state is not getting store/restore correctly - macros change on buttons and bindings is working however they just won't execute - it's like they are locked out.

This may happen on other characters - Rogue with Stealth had a similar issue however I can't reproduce it.

I am not too sure this is normal?

this still happens as of today. /reload seems to fix the issue.

I am not sure what triggers this but i too sometimes have problem with the action bar. a quick /reload fixes the issue but it's pretty rare for me.

imagine a 6 button horizonal action bar, 1 to 6, when i mouseover 1 and click, the 4th sometimes 5th one becomes highlighted and casted. Maybe the issues are the same, you just need to aim a bit left to actually mouseover the button. I play mage and shammy, they both had this problem at some point.

I'll upload and ss as soon as i see the issue triggered again.

I was going to report something somewhat similar to this so I'll just add it here. I think there's some sort of button refresh issue happening (or more likely, refresh not happening) after changes that causes a few different symptoms (button grids visible when they shouldn't be; buttons that can be clicked but nothing happens; buttons not showing up without a reload/relog/going into and out of edit mode). The example above looks like it'll work but here's my quick test scenario:

• Create a new action bar with 1 button, set it to Shapeshift
• Start in caster form
• Put Bear Form on the button
• Hit the button; it should change you to bear and give you a blank button (which is correct)
• Put Bear Form on that button
• Hit the button; it should change you back to caster form and will still show the correct icon
• Hit the button again, note that nothing happens; it'll work normally after a relog and possibly other methods but something isn't happening after the button is originally added that should be, I think

Have the same issue. only happens on bars changed to shapeshift. the button works when u first add it but after changing shape it stops working.

the workaround for me is EDIT each button so #autowrite goes away and then it works reliably. dunno why this matters.

I am experiencing similar issues now that I have been playing my druid.
The autowrite workaround didn't seem to work in my case, however I am going to build a new set of bars for druid today.