I purchased 5 and added 3 without issues.  These are the 8 scene 2342-222. I have two left and they both fail the same way by adding the B button then failing with a pop up that says "The following device could not be added: 54.bc.39 (2342-222) Mini Remote Keypad, 8 Scene v.39 - Cannot add insteon Device. " and an OK option.

I power shutdown and power cycled the ISSY994i. I power cycled the PLM. I did a factory reset on the two minis. I checked that I only have 87 links so not anywhere near the limit. I moved the mini near several switches to ensure they had good wireless connections. I recharged the mini to make sure and they both have a good charge.

 

Edited December 13, 20195 yr by Peter.Cook
got it fixed

Weirdly the B button works and I can make it go on and off. Like the mimi is setup to be one button.

I am running 4.7.3

It really seems like a limit as can add either of the two mini's left and then cannot add the last one. Like there is only one spot left.

It is a limit. Just deleted another device and now get two buttons, A and B when I add the mini.

 

And all fixed. Upgraded to Pro, not sure how to get an easy device count but some quick math with the mini's seemingly counted as 8 each and a number of 8 button switches it seems we it 256 or 300 depending on what I read.

Thank you for the information. It will probably help others with similar findings.

There have been a few other messages about the base ISY994i hitting the limit and adding the Pro feature corrected it.