I'd suggest having a look through this document and following the different troubleshooting suggestions, as there are a few different possible root causes.  If you haven't done already, I'd suggest raising this with Customer Care as they will be able to help narrow down the root cause

Just to clarify, do you mean sync loading of Adobe Tags (Launch) tag manager?

Sorry, I missed this response before. You have two options really:i) sync implementation of tag manager - if you load the tms async then Target will never load quickly enoughii) if you aren't allowed to use a sync implementation (some customers aren't by their dev/IT teams) then the best option woul...

When you inspect the "decisioning.propositionDisplay" event, do you see i) The _experience.decisioning objectii) Does that object include the propositionEventType property & is that populated with something? e.g., display: 1iii) Is the propositions array also populated? Should look something like th...

Yes, in the code I provided the if statement is empty: if (result.propositions) { // Manually render propositions and send "display" event }So if you change it to the following then you'd see the response from Target output to consoleif (result.propositions) { console.log(result.prop...

With the manual process, is that something you would do via the Form Composer or the Visual Editor workflow? If it's the Form Composer then I'd expect you could achieve this with the Create XT Activity API

There is documentation here and the "Load Target Requests" section covers mbox requests etc. There is also a sample app here, which might be useful

Not sure if you have seen it already but there is a sample app here, so you could compare your implementation to that one

Ah ok, for custom mbox activities you just need to pass the name of the mbox in the decisionScopes array. For example:alloy("sendEvent", { "xdm": {}, "decisionScopes": ['activityOneMbox', 'activityTwoMbox'] }).then(function(result) { if (result.propositions) { // Manually render ...

The default behaviour is that the metric will increment against all of the activities the user is qualified for, which use that same success metric. If you want to adjust that default behaviour, there is some more useful information here, in terms of advanced settings like creating dependencies etc,...