We did call about this exactly same issue and got en email from IRCC:
Coronavirus - Maintained status and authorization to work without a permit
We verified the information you provided and can confirm that your work permit application is still in process. If the letter we sent you when you applied online to
extend or change your work permit is now expired and you haven’t left Canada, you have
maintained your status. You can keep working under the
same conditionsof your current work permit until we make a decision on your application.
Here is why the letter expires after 120 days:
- This is the service standard to process this type of application, and
- Many employers and health insurance providers will ask for proof that you’re allowed to work,
- an expiry date helps satisfy their concerns about your status and authorization to work in Canada.
If your employer or others require proof that you can continue to work, you can show them:
- This email,
- The information on our website,
- Your expired immigration document,
- A copy of the Confirmation of Online Application Transmission message in your account,
- Proof that you paid the fees, and/or
- If you received a Request Letter from IRCC, a copy of that letter.
For more information on maintained status, we invite you to consult our
website.