Any and all other Canadian visas are NO LONGER valid once an individual has landed and is a PR.
So YES, "the landing process automatically voids the multiple entry work visa and work permit." (Technically the visa and work permit is cancelled by the landing, not "voided," but in practical terms it amounts to the same.)
If the officer handling the landing fails to make an entry on visas or such in the landing PR's passport, such that there is nothing in the passport showing the visa or permit has been cancelled, that does NOT mean those continue to be valid. On the contrary, even if a visa or permit in a passport APPEARS to be valid, once the individual is no longer a Foreign National, but is a PR, the visa or permit simply is NOT valid.
In the meantime, various theories have been offered in the forum about how and when IRCC records reflect the changes, the cancelling of work permits and other visas. Some of these leave open the possibility of a PR using the visa or permit to facilitate boarding a flight to Canada from abroad without having a valid PR card. As I recall, there have even been some reports here by PRs claiming they were in fact able to do this, to use the visa/permit to board a flight.
Regardless those reports, such visas and permits are NOT valid, and thus cannot be reasonably relied on to facilitate travel back to Canada. Whether the anecdotal reports derive from a delay in technically effecting the visa/permit cancellation, or from incidental idiosyncrasies in how airport personnel abroad screen boarding passengers for proper travel documents, the fact that SOME individuals have successfully used the visa or permit to travel back to Canada (assuming the anecdotal reports are true, which to be frank is a fairly big assumption) offers very little assurance, if any, that another recently landed PR might be able to do likewise.
In other words, there are reports that yes some individuals have been able to use such visas/permits to board a flight back to Canada . . . but those reports do NOT offer any assurance that you will be able to do this. Maybe. But NOT likely.
What you are apprehending is a logistical issue many newly landed PRs face if they have compelling travel requirements in the months soon after landing. So far we have not seen any reliable alternatives to waiting (delaying travel), relying on the PR Travel Document process (which can be problematic for those with pressing time limits), or simply taking one's chances (knowing the PR TD is a backup alternative for getting back to Canada, even if extremely inconvenient).
As already noted, there are possible vagaries in the airline screening process and thus there may be instances in which, due to incidental idiosyncrasies in how travel documents are screened, an invalid but appearing-to-be-valid visa or work permit, in a traveler's passport, will facilitate boarding a flight to Canada. However, the usual procedure for screening travelers destined for Canada is ELECTRONIC, pursuant to which the traveler's information is submitted to an electronic system administered by CBSA, and that system promptly generates a response which simply indicates whether the traveler has authorization to board a flight to Canada, or not.
So, again, based on some isolated reports from a SMALL number of recently landed PRs reporting, without verification, they were able to board a flight to Canada upon displaying a visa, it MIGHT be possible . . . but the system should result in a NO board response for any PR who does not present a valid PR card. The longer it is between the date of landing and the date the PR attempts to board a flight to Canada, the greater the probability the visa/permit will NOT suffice.
