Field gets empty when updating directly from alias (M2M) field

[benhaynes]

From directus created by jasonmarysael : directus/directus#2194

Version Info

• Directus version and branch (Or commit hash): 6.4.9
• PHP version: 7.0.30
• MySQL version: Ver 14.14 Distrib 5.7.23
• Web server: (Ex. Apache, nginx or IIS?) Apache
• OS name and version: "Ubuntu" "16.04.3 LTS (Xenial Xerus)"

So I have a table named "Work categories" which contains an alias field (many-to-many) named "works". When I select one of the works directly from the "Work categories - works" column and try to update the content from an existing (wysiwyg full) field, the field gets empty. When adding a new item or try to update the item directly under the original "work" table I have no issues.