Running the following code in a function:

scoreboard objectives add TempA dummy
scoreboard players set @s TempA 0
stats entity @s set SuccessCount @s TempA
testfor @a {Dimension:0}
tellraw @a [{"text":"Dims "},{"score":{"name":"@s","objective":"TempA"}}]
scoreboard players set @s[score_TempA_min=2,score_GM4_BBLoops_min=300] GM4_BBNState 6

scoreboard objectives add TempB dummy
scoreboard players set @s TempB 0
stats entity @s set SuccessCount @s TempB
testfor @a {Sleeping:1b}
tellraw @a [{"text":"Sleeps "},{"score":{"name":"@s","objective":"TempB"}}]
scoreboard objectives add TempC dummy
scoreboard players set @s TempC 0
scoreboard players operation @s TempC = @s TempB
scoreboard players operation @s TempC -= @s TempA
tellraw @a [{"text":"Delta "},{"score":{"name":"@s","objective":"TempC"}}]
#scoreboard players set @s[score_TempA_min=0,score_TempA=0,score_GM4_BBLoops_min=90] GM4_BBNState 6

scoreboard objectives remove TempA 
scoreboard objectives remove TempB 
scoreboard objectives remove TempC

I've been noticing that any time I run a testfor command that looks for data tags after a stats command, the result would sometimes be constantly wrong (usually resulting in 1)

Sometimes I can get around this by changing the scoreboards name (I did that here with Temp A, B, and C, they were originally another scoreboard) but I noticed the problem persists if you try to perform an operation on the scoreboard after acquiring the stats.
e.g. the code:

scoreboard players operation @s TempC = @s TempB
scoreboard players operation @s TempC -= @s TempA

was originally:

scoreboard players operation @s TempB -= @s TempA

TempC was not used, but this resulted in -1

it was then changed to:

scoreboard players operation @s TempC = @s TempB
scoreboard players operation @s TempC -= @s TempA

This resulted in 0

I then changed it to:

scoreboard players operation @s TempC = @s TempA

This resulted in 1.

based on this, it appears TempA and TempB are both set to 1 regardless of what the stats result is, however the result of this function is:
Dims # (Changes depending on how many people are online and in the overworld)
Sleeps # (Changes depending on how many people are in bed)
Delta 1 (always returns 1 even though it should return the difference between the two numbers)

before I switched scoreboards, both Dims and Sleeps returned 1 as well

This tells me that you can use the scoreboard in a selector and in tellraw, and it returns the true value, but using it in a scoreboard operation returns 1.

The function is located at gm4:modules/better_beds/state/5

Hopefully this is enough information to recreate the problem.
I know this is a problem because I've encountered this numerous times and have also seen many people encounter it as well. reloading or restarting the game doesn't fix this, nor does removing and re-adding the scoreboard objective.

Please thoroughly investigate, as this problem affects a lot of my functions and I would like for it to be resolved!

functions folder available upon request