What are you using to install it? Tinfoil, SXOS? I know i used SXOS to install mine just fine. Other than that try uninstalling it and reinstalling it.
I know that... it is a simple forwarder to the sx.nro at the previous mentioned location. If you don't have the nro in the correct place the nsp forwarder will not work.
I use PowerSaves for amiibo with no problem. I just rewrite the tag as need to what amiibo i need or want. Having a crap ton of tags that can't be rewritten wouldn't be very useful to most as I found with SSBU that you can "update" your amiibo with stats and changes etc for that game. But...
I'm not sure what has been broken since I posted this and easyRPG. Last few updates I've had it won't work right with it. Wasn't till after I posted it and played it did I find out is was incomplete as the original author abandoned the project. So you aren't missing much. I can say the Solarus...
Had something happen to 2 of my 64gb micro sd cards. They wouldn't write or format. Called PNY (the manufacture) and they told me mine are stuck in read only mode and would need to be replaced. Thankfully they offered a lifetime replacement on my cards so they shipped me 2 new ones for free...