Attempting to access TimeSpan.TotalHours gives Common Language Runtime detected an invalid program.

[MauriceCalvert]

Using the expression engine, I add these variables and formulas:

variable "startTimestamp" = "2023-04-01 09:03:25"
variable "endTimestamp" = "2023-04-01 09:34:54"
variable "startlat" = 461706632
variable "startlong" = 61615299
formula "Duration" = "endtimestamp-starttimestamp"
formula "Hours" = "Duration.TotalHours"
formula "StartLatitude" = "startlat/10000000.0"
formula "StartLongitude" = "startlong/10000000.0"

Recalculate throws Exception thrown: 'System.InvalidProgramException' in Flee.dll

The other formulas work as expected:

I've tried "Duration.TotalHours()", same result.

Suggestions to fix this would be welcome