As I had wanted to continue studying but hadn’t received a response from any dev I instead purged my entire database other than the most recent words. Which fixed the issue - this is why it doesn’t give multiple correct answers anymore (and is also when I found our that for some reason an entire column had been removed by the system on ~15 pages worth of words in my database, as I mentioned further up)
Regarding your questions I can answer based on the week I experienced this.
1: It happened for every word that I added and tried to learn, regardless of if I tested on Kanji or English. However, when just ‘reviewing’ the word, it wouldn’t do it all the time, just sometimes. During the ‘learning’ phase, it was always happening.
2: It happened 100% of the time for any word I added. I was also the only one who added words to the course as I had my course closed to the public.
3: I only use my own created courses, so unsure on this.
For information based on what column was deleted… My database and courses are always setup as
Kanji - English - Hiragana
and I then test on kanji > English and english > kanji. Hiragana is just there for the learning/if I make a mistake with the kanji, so I can check the reading faster (rather than having to input it into a dictionary).
I have used this format for ~6? 7? years. However once the repeating correct answers started showing and I decided to delete the database to try and fix it, that is when I found the entire Hiragana column had been removed (the category was still there, just ever word was removed from that column).
what used to be;
勉強する to study べんきょうする
had randomly become;
勉強する to study
Once I had removed all of those broken words, the problems dissapeared, and have not arisen again.
Hope this information helps~