Right off, I would say not "compatible". However, if you've read me, you know I write about "possibilities". So, I never answer that question --"YESANDNO". Cap can be impressed with a Leonine personality, love Leos smile and Grandiosity. Actually love their boldness and smile and sunny nature. But, CAP, after awhile could tire of all that outer charm. Then Cap would ask about substance, and a resume, and sincerity and judgment.
CAP is real. Sincere. A bit of a jokester and deeply confident in its own smarts and abilities.
CAP does not try too hard to make an impression. The Leo might think CAP boring or dull. Oh, Leo would like the genuine smarts and strong abilities.
They both want to Lead and Succeed. Leo could Lead! Cap could Run things. Give them two offices. How this applies to sex and romance and family is more complicated.