I have one of those mounts, also. My phone, Samsung, has the side buttons that are almost perfectly in line with the grips, so I have to move the phone down to where it's almost at the bottom and I worry about the grip. Your cover looks like it takes care of that. What type of phone do you have?
Same with the Nexus 4 I have...I bought one of those industrial strength cases(as seen in pics) that is quite thick on the edges...that fixed the problem by repositioning where the "X" Grips fit.. Search your model # on amazon for a PHAT case. This is the one for mine(chose red for my bike):
https://www.amazon.com/Cocomii-Kickstand-MILITARY-Full-body-Protective/dp/B00XS9GVD0/ref=sr_1_13?ie=UTF8&qid=1489774961&sr=8-13&keywords=nexus+4+caseThey may have one similar for yours.
Unfortunately, I have my phone on a flip case, the cover wouldn't work for me....There's a rubber 'web' you can get to use with these holders that captures the corners of your phone, but they look like they'd be a pain..
By the way, your bike looks great. I really like that color.