Versions 13, 14 and 15 definitely work fine for me on El Capitan, Pasi.
I'm not sure what's up at your end. But if you haven't checked for font corruptions lately, that's always a good idea. A corrupt font can destabilize a Mac and cause lots of problems for these programs.
No, I haven't added any fonts.
But now that I've checked the system requirements for PE13, it says "Mac OS X v10.8 through v10.10" and mine is v10.11.6, so that's the problem. PE15 is supposed to work on Mac OS X v10.10, v10.11, or v10.12, so I'll update my Premiere and hope for the best.
I also heard that Yosemite and Sierra should work fine with PE13.
So, PE13 and MAC v10.11.6 is a bad combination. Fingers crossed I'll try PE15.
I still recommend you check for font corruptions -- and that run a check with the Disk Utility program too. There is absolutely no reason version 13 should not work on El Capitan. It does for me.
I ran the check with Disk Utility and checked the fonts.
PE works fine until I try to render. Then it always crashes.
I bought PE15 yesterday and it works like a charm on El Capitan. So, problem solved. Kinda.
Sorry that it took buying new software in order for it to work, Pasi. But I'm glad that at least solves your problem.