Rails 5 / PostgreSQL 9.5.4 / PostGIS 2.1.8 error with meta-request present

[catalyst-prime]

I'm setting up a Rails 5/Postres 9.5/postGIS app. I have an address object and table that is polymorphic. I can create a single Address object with a geographic point in the standard fashion. Any attempt beyond the first results in :
rake aborted!
fatal: exception reentered
<uers/username>/.rvm/gems/ruby-2.3.1/gems/activesupport-5.0.0.1/lib/active_support/dependencies.rb:287:in `load'

I created a parallel project without meta-request and everything 'just worked'. I added meta-request and the same error came up on the second address created. I removed meta-request from the main project, the error went away.

There may be other gems involved that are contributing to the problem but ultimately, the presence or absence of meta-request was all it took to fail on second object creation.
Error encountered in both rake db:seed and direct manipulation in the Rails console.
"POSTGIS="2.1.8 r13780" GEOS="3.4.2-CAPI-1.8.2 r3921" PROJ="Rel. 4.8.0, 6 March 2012"