I assume your PR card will expire in December. There is no "expiration" of Canadian PR.
In the meantime, however, it appears your application for a new PR card has triggered a formal PR Residency Obligation inquiry, which is PROBABLY what the referral to the local office is about.
This is NOT a referral for Secondary Review. Contrary to a common misunderstanding too oft repeated in this forum, if IRCC has reason to question a PR's compliance with the RO, when a PR card application is made, that typically results in a referral to a local office to conduct the inquiry into RO compliance and NOT a referral to Secondary Review. The importance of this is that the local office process tends to proceed significantly faster than SR and, more importantly, can lead to the issuance of a 44(1) Report and Removal Order terminating PR status (subject to PR's right of appeal).
The fact that you are currently abroad complicates things some. Otherwise, if you were in Canada, the next thing likely to happen is that the local office sends you a request for information and documents regarding your compliance with the PR RO. Or the local office schedules an INTERVIEW. Or both.
Obviously, how you will fare depends in large part on whether you are actually entitled to and are allowed credit toward compliance with the RO based on subsection 28(2)(iii) IRPA (see
https://laws-lois.justice.gc.ca/eng/acts/I-2.5/page-7.html#h-274598 ), oft referred to as credit for time abroad while employed by a Canadian business.
Just the fact that there has been a referral to the local office does NOT necessarily indicate IRCC disagrees with allowing you the credit. The local office might merely review the facts and determine you meet the requirements to be allowed this credit and send the file back to the CPC, so that the CPC can issue a new PR card . . . which might in turn still be sent to the local office again for delivery in person during a counter-interview. (CPC might also deliver the card by mail . . . but . . . well that is another tangent.)
BUT IRCC might not agree your circumstances support being allowed the
employed-abroad-by-a-Canadian-business credit, or at least the local office may question your qualification for the credit.
Actually qualifying for this credit tends to be far more complicated than many if not most PRs apprehend. The criteria are typically STRICTLY applied. So strictly I have often remarked that anyone who actually needs the credit, to be in compliance with the RO, quite likely does NOT qualify for the credit (this is an exaggeration, but not by a whole lot).
You apparently are already familiar with a key element, that the assignment be a TEMPORARY assignment. Many permanent jobs do not last three or four years. For a job that lasts that long, labeling it "temporary" might not be enough for IRCC to conclude it was a temporary assignment. Could DEPEND on the details.
That is just one potential complication.
What constitutes an "assignment" can be tricky.
What constitutes a "Canadian business" is often another rather tricky element for the employment abroad to qualify for the
employed-abroad-by-a-Canadian-business credit.
There are many topics here in which these matters are further discussed, including some doing a deep-dive into some of the pitfalls, complications, and nuances.
How this will actually unfold is difficult to forecast. These can be tricky cases. If IRCC concludes you are not entitled to the credit, you can still make the H&C case that the reason you remained abroad was a good faith reliance on the credit, so you should be allowed to keep PR status.
The particular details in such cases can be so tricky NO ONE here can offer much help in sorting out how to navigate this going forward. Depending on how confident you are that you should be entitled to the
employed-abroad-by-a-Canadian-business credit (after reviewing some of the other discussions about this and reconsidering your situation), you may want to see a Canadian immigration lawyer. That said, you can wait to see what the local office does next before deciding how to proceed.
In the meantime, no need to worry that your PR will expire. The issue is whether or not IRCC will make a decision denying the credit and terminating your status. If that happens you have a right of appeal. Depending on the particular details, the H&C case based on reasonable reliance on the credit may be enough to win an appeal even if the credit itself is not allowed. (Obviously, whether the reliance on the credit is reasonable is a question which also depends on the facts, and your personal relationship to the business looms large in that equation.)