When using an execute detect command from a command block or function that originates in another dimension, will result in false positives.

Example code snippet (repeating command block executing a function within a tickingarea in the Overworld)

execute @e[type=!item,tag=!initialised] ~~~ detect ~ 127 ~ bedrock 0 tag @s add inNether
execute @e[type=!item,tag=!initialised] ~~~ detect ~ 1 ~ air 0 tag @s add inEnd
execute @e[type=!item,tag=!inNether,tag=!initialised] ~~~ detect ~ 1 ~ bedrock 0 tag @s add inOverworld

tag @e[type=!item] add initialised

Expected results-

Newly spawned entities in the Nether to have the 'inNether' tag.

Newly spawned entities in the End to have the 'inEnd' tag.

Newly spawned entities in the Overworld to have the 'inOverworld' tag.

Actual results-

All entities regardless of dimension will get the 'inOverwold' tag.

Possible cause-

Running this same code from a command block located within the End will successfully give newly spawned entities the 'inEnd' tag. 

Running this same code from a command block located within the Nether will successfully give newly spawned entities the 'inNether' tag.

It seems that the dimension that the code is being executed from is not cross-dimension compatible.