Freelance to Full Time - any tips?

I am a web application developer. As such, more than 90% of what I do is all “behind-the-scenes”, which, has no real visualization. I’ve been freelancing for more than a decade now - and frankly getting burned out. I’m thinking about trying my hand in the corporate environment.

My qualifications and experience speak volumes - and I’m getting a lot of interest from Recruiters - some of which ask to see some of my work.

That being said, I’m trying to put together a portfolio. I’m running into a few problems:
1.) The Human Resources / Recruiters I’ve talked to seem to be oblivious to code. They just know what specs (languages) to look for.
2.) Some of the work that I am proud of does not have a front end. Nothing visual. Just lines and lines of code. How do I catch HR/Recruiters attention when all I have to show are blocks of code?
3.) Some of the websites / apps I’ve coded the backend for are being judges on their front end / visual aesthetics. I’m getting feed back from recruiters like “Hey, that looks amazing!”. Great, I’ll pass that on to the designer. How did it function for you? “Oh, fine I guess.” FML!!!

Another issues I am running into is that I am more than qualified for the position, but I lack corporate experience. I’ve been freelancing for more than a decade - thus I must be a maverick and they are afraid I won’t conform to their rules - or maybe I’ll take over their company :wink: lol.

Just looking for some personal tips / experience from people that may have made the jump, as I embark on this adventure.