I don't know which app is at fault here, but since setting up a selection of Hub Global DateTime variables, into which I am only storing a Time, I'm seeing errors like the following intermittently in the Hub logs:
There were hundreds of these errors yesterday evening when I first set the variables up (there are 6 of them). Since then a RM rule has updated them with new times (it runs daily to set start/end times for motion sensors to be active).
When this is done, the variable has a value that starts with "9999-99-99", for what would be "yyyy-MM-dd" in the date formatted string. This will cause a problem for any app that doesn't know how to handle such a value. I don't know if webCoRE knows how to deal with this or not. The full date string is formatted
A valid example of this is: 9999-99-99T11:23:00.000-0700, which is just the time 11:23 AM, with no date. Time values have resolution to milliseconds, hence the 00.000 at the end, and -0700 is the time zone GMT offset.
Something is trashing that date time value: ending with ".046Z" is not a valid time zone value.
You can see the value of the Hub Variable if you want. But, it's easy to see that some intermediary is changing the value by putting a date on it and changing the time zone portion of the string.
In Hub Variables, create a connector for one of those time variables. That will create a virtual device, and you can look at by clicking on the created link. This virtual device will reveal your variable details, like this: