I have seen fewer instant online exchanges this past year but, we've owned timeshares since 1998 and during that time I've seen a lot of fluctuation with the instant online exchanges. So this might be the new norm or it could just be an aberration based on current demands for exchanges.
The biggest online exchange anomaly I've noticed this past year has been with Westgate. Not that I look to Westgate for our vacation exchanges all that much but there are 2 area's I follow, the Great Smokey Mountains and Branson, because Westgate allows us to bring our dogs and they're within drivable distance. The Westgate Lakes use to have a good selection of 2 bedroom units in Sept. and Oct. Not so much these past few months. Instead they're offering a lot of 1 bedroom units. I suspect they're placing exchangers in the small one bedroom lock-off side, then asking an "upgrade fee" if you want the larger side which has the lake view and king size bed.
I think with MVCI it's likely an inventory control issue. I suspect they're holding inventory longer for points users to book internally vs giving up inventory to I.I. for exchange, which works fine for us right now. We've been able to book a couple of 1 night stays using points that will make our travels a little easier and more comfortable. One is a 1 night in a studio unit at Beachplace Towers, because we're flying in/out of FLL and have an early morning flight to catch (keeps us from having to get up @ 02:00 to catch a 06:45 flight). The other is a 1 night stay in a 1 bedroom ocean view unit at Ko'Olina when we island hop to Oahu so our son can explore Pearl Harbor to his hearts content. I'd rather spend the entire day on Oahu than to be watching the time and trying to make the last flight back to Maui.
Inventory control also allows the sale team to make the claim that upgrading in unit size (studio to 1 or 2 bedroom) has been eliminated. While not entirely true, the opportunity does seem to be less than prior to the points program. I do see good availability at most locations if I want to spend points. Not so much if I want to do an instant online exchange. So I believe there has been a shift in the dynamics of exchanging. Requesting a unit will likely result in the desired outcome but, it will be more difficult to accomplish anything except for like for like exchanges except for the resorts that offer only the larger units.