Hi,
I did a quick test and it seems to work on my end (unity 2018.2.18f1, PlayMaker 1.9, latest array maker (downloaded today))
on the 'Hash Table Get' can you try to set the key manually?
Also be sure the the reference (both inspector and actions) has no space, same for key.
Sprite is also supported, maybe the images need to be set to sprite or maybe you have an older array maker version?
If you could not get it to work, what unity/playmaker version are you using?