Adobe Portfolio connect domain - A Record to Adobe Portfolio other A Record to WordPress

Hi,

I struggle a bit with Portfolio when it comes to the DNS and domain handling. The funny thing. It worked already, but now I cannot connect my domain anymore.

Desired outcome

mydomain.com -> Adobe Porfolio
mydomain.com/blog -> WordPress

As this seems difficult or maybe not possible

Accepted outcome
mydomain.com -> Adobe Porfolio
blog.mydomain.com -> WordPress

This setting worked without any issues. But I suddenly got warning emails from Adobe and now am not able to connect my domain to Adobe Portfolio anymore. The site is down.

A Record: www -> Adobe IP1

A Record: www -> Adobe IP2

A Record: @ -> Adobe IP1

A Record: @ -> Adobe IP2

A Record: blog -> WordPress Server IP

According to the help article, there should not be any other A Record. Well, how else should I add a subdomain then?
https://help.myportfolio.com/hc/en-us/articles/216489627-Manually-configuring-a-custom-domain

Right now, I kicked out all other A Records to keep only the A Record related to Adobe Portfolio. I am still not able to connect my domain again. I probably must wait till propagation finishes. 

A Record: www -> Adobe IP1

A Record: www -> Adobe IP2

A Record: @ -> Adobe IP1

A Record: @ -> Adobe IP2

However, how can I solve this issue permanently? What would be my workaround or solution?