The error message told me to post this text when reporting the bug so here it is:

Action:
character.HAIR_SET

Payload:
{"hair":"straight six inches past his shoulders changes color daily"}

Error:
ActionApiError: Invalid JSON response, data object is a string
at new t (https://www.dndbeyond.com/Content/1-0-413-0/React/CharacterTools/dist/characterBuilder.bundle.min.js:17:45742)
at Object.r [as validateResponse] (https://www.dndbeyond.com/Content/1-0-413-0/React/CharacterTools/dist/characterBuilder.bundle.min.js:17:44341)
at https://www.dndbeyond.com/Content/1-0-413-0/React/CharacterTools/dist/characterBuilder.bundle.min.js:44:175992
at r (https://www.dndbeyond.com/Content/1-0-413-0/React/CharacterTools/dist/characterBuilder.bundle.min.js:17:148234)
at Generator._invoke (https://www.dndbeyond.com/Content/1-0-413-0/React/CharacterTools/dist/characterBuilder.bundle.min.js:17:149354)
at Generator.e.(anonymous function) [as next] (https://www.dndbeyond.com/Content/1-0-413-0/React/CharacterTools/dist/characterBuilder.bundle.min.js:17:148413)
at h (https://www.dndbeyond.com/Content/1-0-413-0/React/CharacterTools/dist/characterBuilder.bundle.min.js:17:52311)
at n (https://www.dndbeyond.com/Content/1-0-413-0/React/CharacterTools/dist/characterBuilder.bundle.min.js:17:52982)Actio

the field appears to have a 50 character limit, if you change your description to straight 6" past his shoulders changes color daily  that should avoid the error

Fields with a character limit should limit input to that length.