The call blocker is designed to intercept calls and testing equipment so it will show
a rectified loop short in engineer’s testing equipment. This doesn’t affect your line in the slightest.
The technician should remove ALL of your equipment and run a test without any other interference on the line to see what the issue was all of a sudden, but it isn’t the rectified loop as it was not on the line if your Call Blocker was working fine before this issue arose.
ALL call blockers will cause this reading it does not mean that the issue is from the Call Blocker. I’m confident the problem is with your line or other equipment but your telephone providers technician can advise you of this.