Custom Rails Method Not Updating Attribute - ruby-on-rails

Question

I have a custom method to update a join table row that used to work and is for some reason errorlessly-failing.
The app is a basic course portal with courses and lessons joined by lesson_completions, which have user_ids, lesson_ids, and a boolean value for complete.
The link I'm using looks like this:
<% if #lesson_completion.complete %>
<td class="pr-1"><%= link_to "<i class='far fa-check-square'></i>".html_safe, uncomplete_lesson_path(#lesson), method: :post, class: "text-red" %></td>
<td><%= link_to "Mark as Unfinished".html_safe, uncomplete_lesson_path(#lesson), method: :post, class: "text-red" %></td>
<% else %>
<td class="pr-1"><%= link_to "<i class='far fa-square'></i>".html_safe, complete_lesson_path(#lesson), method: :post, class: "text-red" %></td>
<td><%= link_to "Mark Lesson as Completed".html_safe, complete_lesson_path(#lesson), method: :post, class: "text-red" %></td>
<% end %>
The methods are in my lesson_completion_controller:
def complete_lesson
#lesson_completion = LessonCompletion.find(params[:id])
if #lesson_completion.update_attributes(complete: true)
redirect_to course_module_path(CourseModule.find(Lesson.find(#lesson_completion.lesson_id).id))
flash[:notice] = "Congratulations on completing that lesson!"
else
redirect_to lesson_path(Lesson.find(#lesson_completion.lesson_id))
flash[:warning] = "Oops! Something went wrong!"
end
end
def uncomplete_lesson
#lesson_completion = LessonCompletion.find(params[:id])
if #lesson_completion.update_attributes(complete: false)
redirect_to lesson_path(Lesson.find(#lesson_completion.lesson_id))
flash[:notice] = "Congratulations on completing that lesson!"
else
redirect_to lesson_path(Lesson.find(#lesson_completion.lesson_id))
flash[:warning] = "Oops! Something went wrong!"
end
end
If I use a debugger and look at the value for #lesson_completion on that page it confirms the correct user_id and lesson_id values.
My routes look like this:
post "lesson_completion/:id/complete_lesson" => "lesson_completion#complete_lesson", as: "complete_lesson"
post "lesson_completion/:id/uncomplete_lesson" => "lesson_completion#uncomplete_lesson", as: "uncomplete_lesson"
When I click the button, the server log shows no errors:
Started POST "/lesson_completion/1/complete_lesson" for ::1 at 2020-09-17 15:17:37 -0700
Processing by LessonCompletionController#complete_lesson as HTML
Parameters: {"authenticity_token"=>"HlCIdRVnOJZIHwPqWoJcu3XpNppi5LNSFvL4odU7DsR42Mw6Ld60IXJxzO/8yEw0qX/LH2PuWFuaywP4Ci3VRw==", "id"=>"1"}
LessonCompletion Load (0.8ms) SELECT "lesson_completions".* FROM "lesson_completions" WHERE "lesson_completions"."id" = $1 LIMIT $2 [["id", 1], ["LIMIT", 1]]
↳ app/controllers/lesson_completion_controller.rb:4
(0.1ms) BEGIN
↳ app/controllers/lesson_completion_controller.rb:5
Lesson Load (1.2ms) SELECT "lessons".* FROM "lessons" WHERE "lessons"."id" = $1 LIMIT $2 [["id", 1], ["LIMIT", 1]]
↳ app/controllers/lesson_completion_controller.rb:5
User Load (1.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT $2 [["id", 1], ["LIMIT", 1]]
↳ app/controllers/lesson_completion_controller.rb:5
(0.1ms) COMMIT
↳ app/controllers/lesson_completion_controller.rb:5
CACHE Lesson Load (0.0ms) SELECT "lessons".* FROM "lessons" WHERE "lessons"."id" = $1 LIMIT $2 [["id", 1], ["LIMIT", 1]]
↳ app/controllers/lesson_completion_controller.rb:6
CourseModule Load (0.8ms) SELECT "course_modules".* FROM "course_modules" WHERE "course_modules"."id" = $1 LIMIT $2 [["id", 1], ["LIMIT", 1]]
↳ app/controllers/lesson_completion_controller.rb:6
Redirected to http://localhost:5000/course_modules/1
Completed 302 Found in 19ms (ActiveRecord: 4.3ms)
Can anyone see why this value isn't updating? It used to work and is driving me absolutely bonkers now!