smp1, I purchased an Asrock J5005-ITX (Gemini Lake) in November of 2018 and experienced no HDMI problems when connected to my LCD TV monitor, however, I did have memory compatibility problems with the board. I first tried a Corsair 4gb X 2 dual channel set that did not work with the board. With just a single memory stick installed, or with both memory sticks installed, the board appeared to be dead. Not even beep codes were present unless I removed both memory sticks.
I did have success with a G.Skill 4gb X 2 dual channel set, with the bios detecting the memory as being dual channel. Others had similar memory compatibility problems with the J5005-ITX which are documented on the Asrock forum, link provided below.
I also own an Asrock J4205-ITX (Apollo Lake) board that had an annoying HDMI port blank screen problem. That problem lasted for about a year or two, but was finally resolved by installing the latest bios update.
For what is worth, I ran the Realbench benchmark utility on both boards. The J4205-ITX had a system score of 26,736 while the J4205-ITX had a system score of 13,540.
Asrock forum thread title: Brand new J5005-ITX does not boot
http://forum.asrock.com/forum_posts.asp?TID=8611