Can't add issues from Add Issues modal to boards with Milestone/Assignee lists

When opening the 'Add Issues' dropdown, I get this error in console coming from app/assets/javascripts/boards/components/modal/lists_dropdown.vue

Cannot read property 'color' of undefined

When selecting labels and clicking 'Add issues' submit button, it doesn't add and I get

sentry.39eea7ab.chunk.js:1 TypeError: Cannot read property 'id' of undefined
    at a.buildUpdateRequest (pages.projects.boards.df7b1773.chunk.js:8)
    at addIssues (pages.projects.boards.df7b1773.chunk.js:8)