Bolster automatically applies to the Indi Bubble you have up, and of course the additional power up automatically disappears when Bolster wears off.
For the Luopan (GEO bubbles) it doesn't update automatically. You need to cast a new Luopan AFTER you used Bolster, for the Luopan to benefit from the 2x Potency.
Sadly the opposite isn't true, as the Luopan automatically loses its "power up" when Bolster wears off xD
I wonder why things are like this, but I suppose it's because of the way they handle Luopans (which are tecnically "pets").
For the Indi bubbles they don't have this issue because it's a buff.
For Luopans, since it's a pet, they had to resort to different means.
I think Bolster for Luopans is an undispellable buff granted to luopans themselves when you call them out. This buff has a duration equal to the amount of seconds left on the "Bolster" JA up on the player.
It's just a wild guess, but I think this is how Bolster "works" for luopans.