21766: API Opt-Out/Help Characters Invalid

The campaign submission could not be processed because some combination of the following fields had invalid characters: help_sample_message, help_keywords, opt_out_sample_message, and opt_out_keywords. Please verify that all keywords have alphanumeric and unaccented characters only.

Characters in help/opt-out fields are not allowed.

Use only unaccented alphanumeric characters in message and keyword fields.