It's sitting in a processing queue for documents submitted.
The same department accepts applications too. They digitize cases and documents submitted, then attached to files.
Given the higher load on immigration these days, that department slowed down. When they email you to tell you the docs have been received, then they've made it to the case (been attached).
Anytime after that the officer may check and find them there. That's when they will resume.
As
@sylvain1 said it's usually 60 days (they allow 30 for submission, and they do add a buffer in case you need more time).