Strange behavior with nested IF when using BLANK

Hi guys, 

I'm new to the communtity when it comes to asking questions but I found a bunch of insights here so I hope you can help me with this one 🙂

I'm having problems with Power BI behavior when using a nested IF function. You can see how the functions if defined, and trust me that I tried a bunch of different ways to approach the same problem. For some reason it reads the zero values as BLANKs and then the DAX function doesn't get applied the right way. Is this something that's native to DAX, that it doesn't support nested IF's as well as Excel? Based on this logic the "order in full" should return a 1 not a zero. If I use only one IF statement it works fine for all cases except when the "order in full" is BLANK, so I had to use the nested IF.

Is this error maybe caused by summarised table? 

Thank you guys in advance for your help 🙂