Nsec.app only exports nsec in encrypted form, Amethyst supports it, not sure about others. I'd suggest creating keys elsewhere, i.e. in nak.nostr.com and then importing into nsec.app if you need the raw nsec.

I have been publishing using Habla news and nsec.app just fine. Are you on iOS? Which browser? Anything related to 'blocked popups' etc when you tried to post? 

 I'm on desktop, MacOS. Using brave and I think popups might be blocked. Although I can login, no problem, write, format, etc. But then when I hit publish/post, nothing happens. The Relays get stuck loading but never finish posting to the relays. Its loading forever 

 Try enabling popups when on habla/highlighter, also try keeping nsec.app tab open when posting. Please let me know if it works this way or not. 

 Popups enabled and nsec.app tab open. No luck getting habla to post. All I see is the relays loading. 

I'd love to use to nsec.app instead, so happy to help you bugbash