Repeatable web content structure items causes error and block publishing

Issue

• Reproduction steps:
  1) At Product Menu / Configuration / Instance Settings / Miscellaneous add English (United Kingdom) from Available to Current languages and set it as the default language (this is required to be able to save the provided source snippet of web content structure)
  2) At Product Menu / Content / Web Content / Structures tab, add a new structure with the following settings:
  Set en_GB as language of the structure's Name
  Add name 'Structure - list of dates'
  At Source tab, copy the contents of the prepared structure_narrowed_for_reproduction.txt
  3) Click Save​
  4) At the Structures tab, open the ellipsis menu of the newly created structure and select 'Manage Templates'
  5) Create a new template by the following steps:
  Add name 'List-of-dates-with-opening-closing-info-icons'
  Load script file by clicking 'Choose File' and select the provided list-of-dates-with-opening-closing-info-icons.ftl
  6) Click Save
  7) Navigate the Web Content tab and create a new web content from structure 'Structure - list of dates'
  8) Set a name for the web content
  9) Add a new 'Subtitle' section by clicking the small '+' icon at the end of the row
  10) At this newly created Subtitle section, add a new 'Item icon label' section by clicking the small '+' icon at the end of the row
  11) Click publish

  Expected behavior:
  The web content from structure is published. When creating additional sections, the section titles are actually visible, just in case their first instance.

  Current behavior:
  a) When creating additional sections (e.g. 'Subtitles'), the section titles are not visible (see screenshot).
  b) The web content is not created
  c) The UI actually breaks and errors are shown in browser console

  {color:red}ddm_form.js:4083 Uncaught TypeError: Cannot read property 'get' of undefined{color}

Environment

• Liferay DXP 7.1
• Liferay DXP 7.2

Resolution

• The observed behavior is a known bug and fixed in Liferay DXP 7.1 with Liferay-fix-pack-dxp-17 and above.
• The observed behavior is a known bug and fixed in Liferay DXP 7.2 with Liferay-fix-pack-dxp-4 and above.
• Installing Fix Packs and Hotfixes on Liferay DXP will guide to install these Fixpack in your environment.

Additional Information

• LPS-104414