This seems more likely related to app code than anything perculiar in the transaction manager so I have moved it to the user forum of WildFly.
What I can say:
1. Please replicate this on a more recent version of WildFly. WildFly 10 CR4 was recently released or WFLY 9 if you absolutely must use a .Final
2. You will need to provide more code, ideally a replicator
3. Please include a trace level log