Undefined tag type for 'NonBreakingHyphen'

Hi, we have a machine translation plugin that's having issues with <x> tags in Studio 2015 and 2017.

In the input, we have a tag <x id="NonBreakingHyphen"/> which we are returning as is from our MT engine directly.

However, when doing this via our plugin in Studio, for these segments, we're getting the error:

Undefined tag <0 id="NonBreakingHyphen"/>

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We thought it might be related to the below error resolve in Studio 2017 SR1 but it's present in both 2015 and 2017...

Microsoft Word DOCX (WordprocessingML v. 2):
  • Fixed Internal error: Multiple placeholder tags with the same ID 'NonBreakingHyphen' have different tag properties error when creating new project using a .docx file with hidden text (CRQ-9182).
Any ideas!? Thanks!