Platform (Android, iOS, Website): Website
Browser, if a website issue (Firefox, Chrome, etc) : Replicated in Firefox and Chrome
URLs (aka web addresses) of any relevant observations or pages: first discovered with https://www.inaturalist.org/projects/ecol202-backyard-pitfall-trap-invertebrates. Also works on https://www.inaturalist.org/projects/ecol202-backyard-mammal-tracking, https://www.inaturalist.org/projects/garden-invertebrate-hunt
Screenshots of what you are seeing (instructions for taking a screenshot on computers and mobile devices: https://www.take-a-screenshot.org/):
Description of problem (please provide a set of steps we can use to replicate the issue, and make as many as you need.):
Step 1: go to the project page on the web, tap “Add observations”
Step 2: browse to select a photo from computer, enter location, taxon, date. Fill in compulsory observation fields.
Step 3: The above works fine if saved from there, but here’s the trick. Before saving, also add an additional field (eg “color”). I’ve tried fields with dropdown lists and free text.
Step 4: Tap “Save observation”
Step 5: scratch head, puzzled by why you get an error message like “Your observations couldn’t be added to that project: Missing required observation field: garden invertebrate sampling method” and the all project fields but the allegedly missing one have been duplicated on the project form.
Note that the observation is added to iNaturalist, with all the filled observation fields added, except the one that the warning said was missing (even though it had been filled in).
Tip of the hat to @ ruby_kimber for first noticing this.