Custom Theme Layout Templates Cannot Be Selected in Look and Feel Configuration

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.0.0 DXP FP21, 7.0.0 DXP SP4, 7.0.X EE, 7.1.X, Master
• Component/s: Frontend Infrastructure, Liferay Themes, Themes Infrastructure > Layout Templates
• Labels:
  • liferay-digital-enterprise-70-sp4
  • liferay-fixpack-de-21-7010
• Branch Version/s:
  7.0.x
• Backported to Branch:
  Committed
• Fix Priority: 3
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/49648

Steps to Reproduce:

1. In Portal create a new blank site
2. Set theme for site to Porygon
3. Create a new page
4. Configure for new page (no theme layout templates)
5. Go to look and feel settings
6. Set page to have specific look
7. Select Porygon Theme - Save
8. Open general configuration for new page
9. Custom theme layouts appear but are unusable
10. Select a Porygon layout and click Save
11. Page does not update to new layout

Expected outcome: Porygon custom theme layout template appears and is usable upon selection of theme.