/execute in (dimension) not working properly

I have been converting commands from 1.12.2 syntax to 1.13 syntax over the past few days. Everything is going well until I hit this point.

I have this command running:

"execute in the_nether run tag @p add inNether"

Which seems to work properly. However, in the same function file I have another command:

"execute in overworld run tag @p remove inNether"

Which runs even if the player is in the Nether. This breaks the ability for me to properly track players moving between the Nether and Overworld, which some of my features use to operate correctly.

EDIT: "execute in the_nether" also runs at a player in the overworld too... almost as if the dimension selector is irrelevant to where the commands will run at all.

It used to be this in 1.12.2:

"scoreboard players tag @p add inNether {Dimension:-1}"

to tag only people who are in the Nether.