Unclear why I can't add sheets/drive permission for a custom role

[gcloudfng]

I'm encountering a problem creating a custom role in "IAM & Admin / Roles / Create role" with the intention of granting a service account access to Google Drive and Google Sheets.

Steps I've taken:

• Created a Google Cloud project.
  Did not use an organization
  Enabled the Google Drive API and Google Sheets API.
  Verified both APIs are enabled
  Created Service Account
  Created Custom Role
  Successfully assigned "storage.objects.create" permission to role
  I checked Organization policies, and it's the 12 that the account started with.
  None of them look like they should impact this

• Navigated to "IAM & Admin / Roles / Create role. (really edit)"
  Clicked "+ Add Permissions."
  Filtered by "sheet" nothing shows up
  Paged through a crazy number of permissions, didn't see anything that looks like it would be the permission I'm looking for.

• Navigated to "IAM & Admin/Service Accounts/Service Account/Permissions"
  Clicked on "View By Roles"
  Only "Owner" Hierarchy shows up with Owner account under it.
  Expected to see my service account and custom role
  Clicked on "Grant Access"
  Under "Add Principals" Tried to find custom role, didn't find it
  Entered my service account pseudo email that the system created based off name I gave it
  Clicked on "+ ADD ANOTHER ROLE"
  Large filterable list came up.
  Searched for custom role, sheets, drive, and scrolled through entire list
  Nothing worked
  
  
• Navigated to "APIs & Services/Enabled APIs and Services/+ Enable APIS AND SERVICES /
  Searched "Sheets" under "Welcome to the API Library"
  Clicked on "Google Sheets API"
  Verified "Enabled"
  Clicked on "Manage"
  Clicked on "Credentials"
  Verified that my service account is listed under "Credentials compatible with this API"
  Clicked on pencil next to my service account
  Clicked on "Permissions"
  Found myself back on "IAM & Admin/Service Accounts/Service Account/Permissions"
  
  

Problem:

When attempting to add permissions related to Google Drive and Google Sheets (e.g., drive.files.create, sheets.spreadsheets.create), the "+ Add permission" filter on the custom role I've created for a service account returns no results. I've tried filtering using prefixes like "drive.", "sheets.", "drive.files", and "sheets.spreadsheets", and still, no matching permissions are found.

APIs are enabled: The Google Drive and Google Sheets APIs have been enabled for this project for over 48 hours.

Account Details:

• My account's "Role launch stage" is "Alpha."(?)
  I'm the account owner, but I'm unsure if this "Alpha" status is preventing me from accessing the necessary IAM permissions. To prevent confusion, I didn't specify an organization to avoid having to deal with some sort of hierarchy permission problem.

Questions:

• Is this "Alpha" status restricting access to certain IAM permissions?
  Is there any verification process required to remove this limitation?

Thanks in advance, and apologies if I posted this in the wrong place.