I am experiencing the same issue.
Many of my notes were created using templates and automatically-generated frontmatter using the {{date}} and {{time}} variables.
After updating to version 1.4.5 today, the templates no longer import YAML frontmatter at all.
I do notice that the YAML frontmatter section in the template file is now highlighted red in the default UI:
When I select this file to be imported as a template, it skips over all the frontmatter so that it is absent in the newly-created file.