I ran wunderfixer with verbose:
wunderfixer -v -d 2021-03-24
Using configuration file /etc/weewx/weewx.conf.
Using database binding 'wx_binding', which is bound to database 'archive_sqlite'
Weather Underground Station: KNMALBUQ335
Date to check: 2021-03-24
Number of archive records: 288
Number of WU records: 231
Number of missing records: 57
Missing records:
2021-03-24 06:15:00 MDT (1616588100); 29.976"; 31.8F; 94%;16.6 mph; 82 deg;23.8 mph gust; 30.3F; 0.00" rain ...published.
2021-03-24 06:20:00 MDT (1616588400); N/A ; 32.0F; 94%;15.9 mph; 122 deg;26.3 mph gust; 30.3F; 0.00" rain ...published.
2021-03-24 06:25:00 MDT (1616588700); N/A ; 32.0F; 93%;18.8 mph; 88 deg;20.7 mph gust; 30.2F; 0.00" rain ...published.
2021....