[ThatOneGuy]

Using the lower case equivelents worked...I guess the windows machine didnt like the %R format.

The code I ended with:

Spoiler

new String:formattedMonth[3];
FormatTime(formattedMonth, sizeof(formattedMonth), "%m");
new String:formattedDay[3];
FormatTime(formattedDay, sizeof(formattedDay), "%d");
new String:formattedHour[3];
FormatTime(formattedHour, sizeof(formattedHour), "%H");
new String:formattedMinute[3];
FormatTime(formattedMinute, sizeof(formattedMinute), "%M");
new String:sumpath[250] = "addons/sourcemod/logs/plugin-folder/mappopsummary_<tag1>-<tag2>.log";
ReplaceString(sumpath, sizeof(sumpath), "<tag1>", formattedMonth);
ReplaceString(sumpath, sizeof(sumpath), "<tag2>", formattedDay);
	
new Handle:mappopsummary = OpenFile(sumpath, "a");
WriteFileLine(mappopsummary, "blah");
CloseHandle(mappopsummary);

Thanks for pointing out the null terminator to me (I had forgotten about that). Turned out to be a format issue with windows after all : /

Note: The %H and %M are used in what is written in the file...just in case you noticed they arent used in what i posted above

---------------------------------

Also, as stated in the OP, if anyone knows of a list of formats applicable to windows OS, please post.

-ToG