25+5 Clock Works in Every Way but 6 Tests Failing

I am writing this totally worn out. My project (25+5 clock) started working exactly as per all 29 requirements 4 days ago (from today) and yet it keeps failing the same 6 tests. All of them with the exact same reason ‘Timer has not reached 00:00’.
The tests are Timer test#1, tests - #12, #13, #14, #15 and Audio test#1.
I’ve spent approx. 16 hours over the past 4 days researching high and low, and running the FCC tests suite ad-infinitum but to no avail. All the while my clock works exactly as per all 29 requirements.
For each of my FCC certifications, I have completed all test projects with all tests passing (no exceptions) and there were several previous certification test projects in which I was held up due to failing tests but I always, repeat always, was able to solve them by following the FCC guidance of 'Read-Search 'alone. I never had to ‘Ask’. But with the 25+5 clock project, I am totally perplexed as everything works but the same 6 tests fail. The words, ‘Timer has not reached 00:00’ are etched uncomfortably on my mind. I am a dedicated learner and as I said, all of my previous certification test projects not only work but pass all tests. Honestly, I do feel a bit frustrated that a totally working project is being rejected for no apparent reason. I’d be super grateful for any meaningful suggestions especially from FCC members.
Thank you in advance.

My project in codepen is here

Safari/537.36

Challenge: Build a 25 + 5 Clock

Link to the challenge: