I assume you get this as a string somewhere -> In Format() with format pattern
In Format("20260627 160152", "Format Pattern", "<YYYY><MM><DD> <hh24><mm><ss>")
This should convert it to JMP's datenum which you can then format as needed by using column properties for example. If you have the value in a column, you could try to mess with direct format pattern formatting, but using formula with In Format() is safer option (and easier to use in my opinion).
-Jarmo