Front of single cloze card not showing at all, can only see card and answer once I click forward

Several cards don’t show anything on the front at all, not even an error message. Only after I click to reveal do I see the original card along with the answer. These cards were fine before I added Ankihub add-on, and I need them as they are useful cards. I have not made any changes to the cards, and the cards only have one cloze (c1) to reveal.

Please help, this issue is widespread in my deck.

On Anki, go to the top left and find tools, then click on empty cards, then press delete