Duplicating worksheet causes formatting and data to go haywire

Hi, I'm having a slightly odd problem I thought I would ask for help with. I have a workbook that lists my clients (I'm a tutor) and, in order to make future weeks, I've been copying sheets and duplicating them. Now at an earlier stage this appears to have worked fine as in my workbook I have multiple sheets with similar formatting. For some reason, I cannot get any sheets to properly duplicate anymore. I can show what happens with the attached screenshots, progressing from screenshot 1 to screenshot 4. The formatting goes haywire and most of the data seems to disappear. I've copied sheets successfully before so I have no idea what might be happening. Any help would be much appreciated.

I can provide more information if anyone needs it -- the problem is bizarre and I can't find any help anywhere.

test.xlsx I've attached a copy of a sample worksheet here -- I tried duplicating this and likewise the formatting and data went haywire. Would anyone else be able to try this and give me some pointers as to why this might be happening?