The best way to test this is by QA'ing your app. Most likely there is a call being made to the collection servers that does not have any values sent that define the Custom Link. Here's my suggestion:
1 - use Workspace in order to try to narrow down "when/where" the custom link is called. One idea is to use Flow reporting. Use Custom Link as the dimension being analyzed in the Flow component and find the unpleasant "AMACTION:". Click to see what the previous Custom Link was. Or, switch the previous column to Page to see what screen the Custom Link is getting called from.
So after that QA'ing, we discovered that it was the generci AMACTION launched on some app actions.
We managed to find the AMACTION that was not sending infos on the action and we added 'Generic + pageNAme' to it. Now we know where are this pop'ins coming from. Further more, if we breakdown with our clic Evar we get all the infos !
But now we discovered another IOS Customlink that we don't know how to make use : "ABDINTERNAL:Lifecycle".
This custom links is launched alot, but to what use ? and from where ?