Steps to reproduce:

1. Create script type item with this content:

   return '<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>\
   <status>\
       <output>\
           <channel num="1">\
               <message>no&#xa0;ttx&#xa0;data</message>\
           </channel>\
           <channel num="2">\
               <message>ok</message>\
           </channel>\
       </output>\
   </status>' 

1. Sets item preprocessing:

   1. XML to JSON
   2. JSON Path: $.status.output.channel.[?(@['@num'] == 1)].message.first() 

1. Create trigger for item with expression:

   in(last(/test/test.in),"ok","no ttx data")=0 

1. Wait 1m whet script will be execute

Result:
Trigger staus: PROBLEM
Expected:
Trigger staus: OK