When the 2Pack contains a Process Parameter that is a direct table to a table that is also imported by this 2Pack, during the packin process, the getAD_Table() from MRefTable instantiate an object from MTable whit MTable.get(Properties ctx, int AD_Table_ID) and as the transaction is not passed the Table is not found by MTable so the system throws an exception. Solution suggestion:

Class: org.compiere.model.MRefTable
Line: 62
Original code: MTable table = MTable.get(getCtx(), getAD_Table_ID());
Code changed: MTable table = MTable.get(getCtx(), getAD_Table_ID(), get_TrxName());