SRWare.net

I would like to signal a bug in the browser, the blocking exceptions of third-party cookies will not work. In fact, the browser continues to block cookies from websites/domains included in the exceptions and consequently the login to the sites.

you have to tell Iron to allow 3rd party cookies (also) for subdomains if you use them

for example subdomains on example.com ==> just set the exception to this:

Update - Solved! I had to add another domain link for that site, now login works.
It's non bug!
SRWare Iron is great browser!