Actually, yes, I've noticed that it's gotten harder to reliably purchase items via double-click.
Sometimes it just doesn't register, so you have to do a second double click.
The available shop range also appears to be too short for the Summoner's Rift spawning platform.
You can still be within healing range but out of shop range, yet the shop will be open anyway.
So you can click all you want, but no item is purchased, so you have to close the shop, move forward towards the spawn point, then open the shop again.