Cannot find gem even though bundle reports it is installed - ruby-on-rails

Question

I am attempting to install kaminari, but Rails cannot find it or a dependency (I've run into both - currently dependency):
∴ bundle exec rails g kaminari:config
Could not find i18n-1.8.4 in any of the sources
Run `bundle install` to install missing gems.
This is despite it being installed:
∴ bundle info i18n
The dependency tzinfo-data (>= 0) will be unused by any of the platforms Bundler is installing for. Bundler is installing for ruby but the dependency is only for x86-mingw32, x86-mswin32, x64-mingw32, java. To add those platforms to the bundle, run `bundle lock --add-platform x86-mingw32 x86-mswin32 x64-mingw32 java`.
* i18n (1.8.4)
Summary: New wave Internationalization support for Ruby
Homepage: https://github.com/ruby-i18n/i18n
Path: /Users/shawn/.rvm/gems/ruby-2.6.3#refstats/gems/i18n-1.8.4
I first attempted to delete Gemfile.lock. Same result. Then I deleted the refstats gemset and recreated it. Same result. Then I tried bundle install --force and got same result.
I've tried both gem 'kaminari', '~> 1.2' and gem 'kaminari' in my Gemfile.
Any suggestions?
EDIT:
Gemfile:
source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }
ruby '2.6.3'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '~> 6.0.3', '>= 6.0.3.2'
# Use sqlite3 as the database for Active Record
#gem 'sqlite3', '~> 1.4'
gem 'pg'
# Use Puma as the app server
gem 'puma', '~> 4.1'
# Use SCSS for stylesheets
gem 'sass-rails', '>= 6'
# Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker
gem 'webpacker', '~> 4.0'
# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
gem 'turbolinks', '~> 5'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.7'
# Use Redis adapter to run Action Cable in production
# gem 'redis', '~> 4.0'
# Use Active Model has_secure_password
# gem 'bcrypt', '~> 3.1.7'
# Use Active Storage variant
# gem 'image_processing', '~> 1.2'
gem 'devise', '~> 4'
gem 'kaminari'
# Reduces boot times through caching; required in config/boot.rb
gem 'bootsnap', '>= 1.4.2', require: false
group :development, :test do
# Call 'byebug' anywhere in the code to stop execution and get a debugger console
gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
end
group :development do
# Access an interactive console on exception pages or by calling 'console' anywhere in the code.
gem 'web-console', '>= 3.3.0'
gem 'listen', '~> 3.2'
# Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
gem 'spring'
gem 'spring-watcher-listen', '~> 2.0.0'
end
group :test do
# Adds support for Capybara system testing and selenium driver
gem 'capybara', '>= 2.15'
gem 'selenium-webdriver'
# Easy installation and use of web drivers to run system tests with browsers
gem 'webdrivers'
end
# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
Edit 2:
∴ cat .ruby-version
ruby-2.6.3
I have no .ruby-gemset, but my console is reporting I'm using the right one:
12:36:50 shawn#macbook-pro:~/Documents/uga/refstats (git:master:547a0b4) ruby-2.6.3#refstats
∴
EDIT 3:
Well, the gremlin has disappeared, though I cannot say why. This is what I did:
1) Created new test rails app
2) Bundle install in new gemset
3) Added kaminari to Gemfile
4) Bundle install
5) Generated kaminari config successfully
6) Switch to non-working app, but forget to switch gemset, putting me in rvm with no gemset. Don't notice.
7) Bundle install
8) Notice things get installed, including kaminari. Notice I'm on wrong gemset.
9) Switch to correct gemset.
10) Bundle install (which installs nothing)
11) Generate kaminari config successfully
I really cannot say why it started working, unless installing to the rvm root had some effect. But that's what I did, and it's all working now. Thanks for the time.

Answer 1

Just because the gem is installed on your machine does not mean it is part of your bundle. bundle exec scopes the available gems to only what is included in your Gemfile and those gems dependencies. See if i18n for that version shows up when you run bundle show.