I have a big problem with permalinks.
When I do that change, I wanna use the popular Permalinks Migration Plugin, which would redirect visitors from the old to the new address.
But that's the problem: the plugin works perfectly with all posts, which have IDs of the type XX, XXX, XXXXX, but not with posts of the type XXXX - that is, 4-digit posts can't be redirected to the new address and I get a 404 error.
At the same time, I have a heavy database query, and for that reason I've reverted to the old variant, until the problem's solved.
To be concrete, here's an example:
I've also tried the plugin Permalinks moved permanently, but it fails just in the same manner.
Could you please tell me, where the problem comes from, how could I solve it, and whether it's removed in the last WordPress version? Currently, I'm using 2.8.6
Thank you in advance for the kind support!