There are a few safety functions for drinking potions that could be preventing that.
Accounts with <15 hp will not sip any divine potions (including ranging). Otherwise, the bot will only be allowed to sip ranging potions if it sees that you are ranging (either enable ranging mode on the Main tab) or wield a bow/arrow. Maybe you are using a newly released item for ranging which the bot doesn't support yet, tell me what weapon/ammo you have so I can add it to the supported list
Otherwise:
You sure this one is enabled? (Mouse)
If so, then what about the ranging part here:
The default value is set to 3 levels apart, maybe try lowering the number to 2?