I've noticed that whenever I try buying something from user shops or the Subeautique with the exact amount of sP the item is priced at, it tells me I don't have enough to buy it. But if I take out just a little bit of extra sP, I'm allowed to buy the item.

User shops and Subeautique are the only two places I've personally noticed this, but I suppose there could be others.

i'm having the same problem, not sure what the cause is but it is quite annoying :/

I am having the same issue with user shops!

It is not occurring within main shops

yep, still seems to be so. i just tried to buy a 500sp item with exactly 500sp on hand and got the error.

seems to be working now :)