Categories not imported

## Describe the bug
When importing a BlogML file (exported from this module on a different site), the categories are not imported.

## Software Versions
- DNN: 09.02.00 (366)
- Module: 6.4.1

## To Reproduce
Steps to reproduce the behavior:
1. Create a simple vocabulary for categories
2. Select vocabulary in the Blog Module Settings
3. During import check the checkbox to create missing categories
3b. Or create categories manually in vocabulary
4. After import all blog posts are imported, but category information is missing

## Expected behavior
Categories are created and associated to blog posts

## Error log
**Note: Debug DLL's**
Please replace the current extension DLL's with the debug DLL's (if these are available with the release) and reproduce the error with the debug DLL's before pasting the error log.

Paste the error log that is related to this issue.

## Additional context
Add any other context about the problem here.