Unable to import a .mctemplate with a behavior pack included in 1.6.0.

Verification builds:

Ver. 1.6.1, Win10 Build 1.6.100.0

Summary:

.mctemplate file with a behavior pack fails to import.

Impact:

Pre-Submission testing.

Repro Steps:

Create a template package with a behavior pack.

Observed Results:

"Failed to import 'my_template' See output log for more details".

Expected Results:
Template Import OK

Screenshots/Videos attached: Yes/No

Regression Build

Did not work in 1.6.0. First time we have made a bahavior pack.

Notes:
I am trying to import a .mctemplate with a behaviour pack but it says "Failed to import 'my_template' See output log for more details".
In the log there are 'No errors were found'.
If I zip up the resource and behavior packs on their own, they imports ok as .mcpack files.
The template loads ok, if i remove the behaviour pack files.
The pack validates with the ContentValidator_1.6.1 tool with no errors.