When using a grantlee theme, the date it shows is not the same as the date shown by the built-in themes. Namely, the grantlee theme is wrong in the sense that it ignores the time zone difference. For example, I have a mail sent at 8:36:25 +00:00, which is shown (correctly) in my time zone as 10:36 by the built-in themes, but is shown as 8:36 by the grantlee themes. Reproducible: Always
I experienced this too, around version 5.3.0, I think. However, it is fixed for me now. Do you still experience this, in a reasonably recent version? I'm afraid the version you reported this bug for (4.14.10) has long been unsupported now.
I was fix in 5.4.0 Regards