Thanks for your reply. Your suggestion works great. At least now I can clean out the duplicate Actions and avoid the conflicts I'm currently having.
I've only started using LC Designer and I suspect some of my "actions" might be causing the disappearing Actions in Action Builder. I've been copying and duplicating parts of the form I'm building (to save work!) and I suspect, if an Action is included, this might confuse the program. LC is pretty good at renaming items (adding (0), (1) etc) in the Hierarchy to make everything unique but, I've discovered its always best to change these names to avoid problems. I've also discovered that if I completely recreate the Actions causing me problems they don't disappear.
I have not been able to reproduce the issue you are having, but I might be able to help you with the other part of it.
Here's a screenshot of a sample form with two actions created with Action Builder.
And here is the XML for those actions.
Notice that the Action Builder script ALWAYS starts with //+ GENERATED and it always ends with //- for every individual action. For instance, the first action removes an instance of the blue subform, and the second one removes an instance. If you have duplicate entries, you could locate the entry in XML and delete all of the lines from //+ GENERATED to //- (inclusive, of course). That should eliminate the duplicate entries.