https://clusterfuzz-external.appspot.com/fuzzerstats?fuzzer_name=libFuzzer_chewing_fuzzer&job_type=all
chewing_fuzzer seems don't run with data files.

Could you please check the fuzzer and data files are at the same location when it run?
If it run with data files, "cov" should be more than 500 easily and find crashes quickly (much less than 5 minutes).