Does this issue relate to a new feature or an existing bug?

• Bug
• New Feature

What version of Serilog is affected? Please list the related NuGet package.
Serilog 2.8.0

What is the target framework and operating system? See target frameworks & net standard matrix.

• netCore 2.0
• netCore 1.0
• 4.7
• 4.6.x
• 4.5.x

Please describe the current behavior?
The hex numeric format specifier does not work unless supplied using standard C# string interpolation. This means I cannot use structured logging if I wish to retain the formatted string in the standard log output.

int status = 16;

log.Error($"Status [0x{status:X8}]"); // "Status [0x00000010]"
log.Error("Status [0x{status:X8}]", status); // "Status [0x16]"
log.Error("Status [0x{0:X8}]", status); // "Status [0x16]"

Please describe the expected behavior?

int status = 16;

log.Error($"Status [0x{status:X8}]"); // "Status [0x00000010]"
log.Error("Status [0x{status:X8}]", status); // "Status [0x00000010]"
log.Error("Status [0x{0:X8}]", status); // "Status [0x00000010]"

Apologies in advance if this is not how it's meant to work. I tried looking for documentation addressing this specific case and couldn't (easily) find it, however, https://github.com/serilog/serilog/wiki/Writing-Log-Events states:

Message templates are a superset of standard .NET format strings, so any format string acceptable to string.Format() will also be correctly processed by Serilog