My Lawn program was set to water relative to Sunrise and has failed to water (doesn't show in the history at all) on several days.

This seems like the same issue reported by others over the last year or so (e.g. here, here, here), but it was reported fixed in firmware: 06/12/2019 | v4.0.993/v.4.0.1122/v.4.0.1131
(Fix for End by Sunrise/Sunset option issue that might prevent long running programs to start)

So I'm not sure if its the same bug and a continuing know issue, or a new one with the same symptoms?

(We had an issue with under watering last year, but didn't piece this together until now. Same symptoms, so appears likely.)

Log from latest run that appears to have been triggered, but never actually ran the watering and finished almost immediately. Also, no entry for that program appears in the watering history (not even with 0:00 watering time)

Log:

2020-06-04 03:43:48,122 - INFO  - rmThreadWatcher:438 - **  Automatic Update: Starting update check as interval to next watering program is bigger than 3600
2020-06-04 03:43:48,537 - INFO  - rmMainManager:513 - ** Automatic Update: No updates available
2020-06-04 05:45:49,478 - INFO  - rmParserManager:509 - ** Forcing parsers run because program 4 will start in 540 seconds
2020-06-04 05:45:50,822 - INFO  - noaa-parser:115 - Fetching Hourly data from https://noaa.rainmachine.com/xml/sample_products/browser_interface/ndfdXMLclient.php
2020-06-04 05:45:51,437 - INFO  - noaa-parser:370 - probability-of-precipitation 12 hour: reject date 2020-06-03 20:00:00 as it's in the past
2020-06-04 05:45:51,561 - INFO  - noaa-parser:119 - Fetching Daily data from https://noaa.rainmachine.com/xml/sample_products/browser_interface/ndfdBrowserClientByDay.php 
2020-06-04 05:45:52,671 - INFO  - rmSimulator:614 - * Correction: Zone 7 et0Delta=0.19, qpfDelta=0.87, rain=None, realPrecip=2.06, qpfUsedLimited=1.19
2020-06-04 06:10:02,334 - INFO  - rmProgramScheduler:262 - Program 5 added to watering queue and/or watering history
2020-06-04 06:10:02,473 - INFO  - rmProgramSchedulerWatering:250 - Watering - starting zone: (uid=None, pid=5, zid=7, ust='2020-06-04 06:10:00', rst='2020-06-04 06:10:02', ud=368, md=0, rd=0, aw=8.4570869152244832, flag=6, manual=False, running=True, flowClicksDelta=0)
2020-06-04 06:10:03,647 - INFO  - rmProgramSchedulerWatering:295 - UpdateZone available water: 8.45708691522
2020-06-04 06:10:03,716 - INFO  - rmProgramSchedulerWatering:150 - Watering - zone finished: (uid=None, pid=5, zid=7, ust='2020-06-04 06:10:00', rst='2020-06-04 06:10:02', ud=368, md=0, rd=0, aw=8.4570869152244832, flag=6, manual=False, running=False, flowClicksDelta=0)
2020-06-04 06:10:03,751 - INFO  - rmProgramSchedulerWatering:160 - Watering - program finished: programId=5 flag=6
2020-06-04 08:28:03,173 - INFO  - rmMainManager:239 - Upgrade checked.
2020-06-04 09:23:11,882 - INFO  - rmMainManager:239 - Upgrade checked.