I had +5 hydra on my helmet. I rolled for my 25% and it gave it to my +hydra but instead of saying +6 it stayed +5 just turned blue. I’m heartbroken. It’s so hard to roll for the +stat slot and get it. Not only that, but I lost the 25% roll bonus either way because it stayed at 5. Please help 
You need to understand masterworking on +stats.
Master working is based of the starting value of the stat, not the current value.
For a starting value +4 at start you actually will have a Greater affix on this stat. So the masterworking goes off the max non-Greater Affix value (3).
4.00 + (3.00x.05) = 4.15 (Rounded to 4)
4.15 + (3.00x.05) = 4.30 (Rounded to 4)
4.30 + (3.00x.05) = 4.45 (Rounded to 4)
4.45 = (3.00x.25) = 5.20 (Rounded to 5)
5.20 + (3.00x.05) = 5.35 (Rounded to 5)
5.35 + (3.00x.05) = 5.50 (Rounded to 5)
5.50 + (3.00x.05) = 5.65 (Rounded to 6)
5.65 + (3.00x.25) = 6.40 (Rounded to 6)
6.40 + (3.00x.05) = 6.55 (Rounded to 7)
6.55 + (3.00x.05) = 6.70 (Rounded to 7)
6.70 + (3.00x.05) = 6.85 (Rounded to 7)
6.85 + (3.00x.25) = 7.10 (Rounded to 7)
Of course you need to adjust this or lower versions of stats.
That’s insanely lame. Thanks for the heads up. How disappointing. I appreciate your reply.