I'm not sure what is causing this but randomly while playing on a realms server (in creative) EasyPlace won't select/grab the correct block for me and place in my inventory. It forces me to get the proper block manually and then place. Otherwise I get the "Action prevented by EPM" message.

What's weird is that its been working fine for a while now and this randomly happened, and going into a SP world has EPM working just fine.

It's probably the new pick block behavior, check here: #588 (comment)

Version 0.12.5 will at least add a warning for when that happens.