Difference between two measures

Evening,

I've calculated the proportions between a table of Group Sizes and the number of group sizes & Table Sizes and the number of those tables.

When I attempt to calculate the difference between these two measures (m1 - m2) instead of finding the difference, I'm presented with different values depending upon which Size column i use from either table (Group Size or Table Size) as well as either of Sizes gives a dramatically different value. In some cases the numbers should equal 0.5, but they instead somehow equal 0.9 or -1.1.

There is a relationship between both tables, I have tried setting it to both single and both. I have tried using variables, yet it doesn't seem to want to come together.

Here is a picture of the page: https://gyazo.com/d468848286364a3ee6f65cb2976dcc13

Top right hand corner, Customer Grp Proportions are the numbers for m1.

Bottom right hand corner, Table Config Proportions are the numbers for m2.

NumberOneG and NumberT are the difference by doing m1-m2

NumberTwoG and NumberTwoT are the difference through using variables var1-var2

Instead of GroupSize/TableSize showing the difference for Catergory 1 as 0.53, it's showing these values.

I'll link a pbix if anyone wants me to.