Safari 12.1.x problem with using certificates

I have and application which is using Crypto Token Kit and I have certificates which I could use on web pages. The application is working on the Safari version 12.0.3 and Google Chrome. For the Safari in version 12.1.x I have been asked for the choosing certificate but I got error afterwards. Change log of Safari telling about improving security. Does anyone know how to get an infrormation about it, or found similar problem.

Thank you in advance!