I passed the speech check to let Mick show me his 'special' inventory. On later visits, neither Mick or Ralph's trade screen opens up. In dialogue, they say "sure, have a look", and then dialogue screens just ends. Has anybody seen this?

I'm also very disappointed that Mick doesn't sell everything you see in his secret cache.

You have to follow Mick to his hidden cache/weapon room.

Yep. Did that the first time. Now when I follow him in, he won't trade. Neither will Ralph.

I've got this bug also, the past two play sessions. They -say- they're opening up the store, "take a look", etc, but no store menu opens, not for either NPC.

I have not had this issue with any Vendor. However Vendors will not sell when they are not scripted to. So, if you are in the store outside of their hours, then they may not sell to you even though you can talk to them.

Not sure if Mick or Ralph has a schedule or not.