Maybe your issue has something to do with the migration issue explained on page 68 of the release notes:
Issue: hcihrlconvert
Description: hcihrlconvert is used to add the {ACTIVENULLWHENNOCONTENT 1} key into any VRL/FRL segment in an HRL file.
Usage
hcihrlconvert [hrl …]
Where: hrl is the HRL file to convert. Specifying no argument converts all HRL files under the site.
The ACTIVENULLWHENNOCONTENT key is used to change the parsing and encoding behavior on a empty VRL/FRL segment in an HRL file.
In versions earlier than 6.1, the behavior was to set the empty VRL/FRL segment as ActiveNull.
In versions 6.1 and later, the default behavior is to fill padding characters for empty VRL/FRL segments.
For example, if you have an xlate file which uses Repeat While on an empty VRL/FRL segment in a HRL, set ACTIVENULLWHENNOCONTENT to 1 for the VRL/FRL segment in the HRL. This is set through the GUI (by selecting Active Null) or by using hcihrlconvert on the command line.
If you have no requirement to use HRL in this way, then do not select Active Null on the GUI. This makes the engine use the new behavior.