[Bug] - Pod Installation Error

[dannyvfilms]

Summary
When trying to install the mailcore2-ios pod, an error message appears during the process. The error occurs specifically when trying to build for iphoneos16.4 where it mentions 'Unknown build action 16.4'.

Platform(s)

<iOS>

Happens on Mail Server

<Not Applicable>

Piece of code
Here is the content of the Podfile:

platform :ios, '9.0'

target 'mailcore2-test' do
  use_frameworks!

  # Pods for mailcore2-test
  pod 'mailcore2-ios', :git => 'https://github.com/MailCore/mailcore2.git', :tag => '0.6.4'

  target 'mailcore2-testTests' do
    inherit! :search_paths
    # Pods for testing
  end

  target 'mailcore2-testUITests' do
    # Pods for testing
  end
end

I ran the command pod install in Terminal.

Actual outcome
Cocoapods was unable to install the mailcore2-ios pod, returning the following error:

xcodebuild: error: Unknown build action '16.4'.

Connection Logs

N/A

Expected outcome
MailCore should successfully install via Cocoapods when I run pod install.

Link to sample code on GitHub reproducing the issue (a full Xcode project):

N/A

Here are the version details of my local setup:

• Homebrew: 4.0.20
• Ruby: 2.6.10p210
• Gem: 3.0.3.1
• Cocoapods: 1.12.1

I have already tried different troubleshooting methods such as correcting the Xcode command line tools path, manually downloading the MailCore2 repo and adding it to the Xcode project, and attempting to add it via Swift Package Manager (the package manifest at '/Package.swift' cannot be accessed (/Package.swift doesn't exist in the file system)), but none of these have resolved the issue.