Actually over the last one month i have been providing a few IDs everyday from India and nearly everyday 1-5 of these observations everyday have missing dates and i am guessing this is a related issue.
I briefly used the iNat app a few months ago and i noted that when i had spotty network there was a lag in picking up location and time so they picked different location and so on especially when i used iNat app directly to upload an observation instead of say taking a picture on phone and uploading via iNat app. They showed missing time or location and sometimes even said observation missing and could never be recovered.
This month i have been frequent in uploading pictures via laptop. I note that edited pictures can sometimes have missing time and location. I had used photos by mac . Drag and dropped pictures had had missing metadata. I then tried by exporting and uploading. Safari still missed picking up metadata. I had to manually enter location and time. But Brave browser picked up the metadata. I also think clearing cache and reducing the number of observations while uploading can help in picking up the location and time better. Uploading 50 pictures at a time seem to load metadata better than say 100 or 150 pictures at one go.