The class JCAServerTransactionHeaderReader is placed under package com.hp.mwtests.ts.jta.jts.tools. which means is not available during runtime of tooling. As the header reader is used by com.arjuna.ats.arjuna.tools.osb.mbean.ObjStoreBrowser it brings situations where the record can't be loaded by tooling. The browser seems to be used by Expiry Scanner and that suffers by that fact.
The WFLY start sequence contains info of not possible to load the reader when the object store contains some unfinished jca subordinate transaction.
The point is to move the jca reader under jts tooling package to be compiled and distributed in the jts jar.