Halline nods to you and says, "Looking for something to do, Peppwyn? I've got just the thing for you. If you want to know more, simply ask me about BOUNTIES."
>ask hal about bounty
Halline says, "Hmm, I've got a task here from the town of Icemule Trace. The local healer, Mirtag, has asked for our aid. Head over there and see what you can do. Be sure to ASK about BOUNTIES."
>shake head
You shake your head.
>ask hal about removal
Halline says, "You want to be removed from your current task assignment, Peppwyn? If so, ASK me about REMOVAL one more time to confirm this choice."
>ask hal about removal
Halline says, "Very well Peppwyn, I have removed you from your current assignment."
>w
[Adventurer's Guild, Office
Neatly appointed and exuding a brisk, business-like air, the office holds only a trace of the warmth given off by the fireplace in the lobby. An octagonal display case occupies the back of the room, partially blocking the walkway to a sturdy mithril-barred door that takes up a good portion of the rear wall. A tall apothecary desk stands parallel to the west wall. You also see Guild Headmaster Elrith.
Obvious exits: east
>ask elri about exemption
Elrith says, "You must specify one type of task that you wish be exempt from. Valid tasks are: Kill Creatures, Retrieve Heirloom, Procure Skins, Procure Gems, Protect Traveller, Procure Herbs, Kill Dangerous Creature, Rescue Child, Kill Bandits. You may also specify NOTHING to remove your existing exemption choice."
>Procure Herbs
Elrith says, "You already exempt from the Procure Herbs task, Peppwyn."
>
You feel more refreshed.
>

I believe your exemption preference registers with the guildmaster but you need an active waiver for it to actually work. But when you fire it up, it defaults to what you last requested.

Its not included in the clip, but I can see from the in-game logs that what happened is that you were assigned the Gather Herbs task and then activated a Login Rewards BOOST WAIVER seconds after getting it. The waiver only stops you from getting assigned a new Gather Herbs task -- if you've already gotten one prior to activating the boost, you'll still have that task. (And, indeed, for the hour after that, you were also not assigned any further Gather Herbs tasks).

Coase

>If I BOOST WAIVER today, will I be exempt from herbs, or do I have to go visit the big boss each time?

It'll keep whatever you've chosen last as your exemption. So, if the last thing you've asked to be exempted from is herbs, any subsequent waivers you use will be herb exemptions until you choose to change it.

Coase