Newbee re potting zygo question

[Nedski7]

Hello
New to the forum and orchids been dabbling over the years. I have had great success with the standard home Depot orchids . So I started going to the local orchid show to acquire different varieties.
I have a 5 year old zygo my first non home depot orchid . It has tripled in size and has out grown it's pot. The new shoots have starting to grow horizontal so it's time . I watched some videos . About repotting in all the videos the orchid were basically a train wreck with lots of rotted roots and involved lots of to remove old media and rotted roots
My zygo doesn't have a single rotted root and the plant is super healthy looking . I couldn't separate the roots if I wanted to. My concern is the old potting medium that I can't reach in the center . Will this cause a future issue? Can I simply just up size to the next pot and fill the 1/2 gap with new potting bark ?
Regards
Ned