We have corrections for the Filet Jumper on p.52 from issue 59
The yarn weight stated should be 4ply, and not DK.
It appears that the 4.5mm hook stated is too large to achieve the tension stated. You could try a 4mm hook, or even a 3.5mm hook. It’s very important to work a tension swatch before you start to check that your hook size is giving you the tension stated in the pattern. Particularly in this case, where the 4.5mm hook is obviously too large, please do a test swatch to find out which size of hook with give you 8.5 filet squares to 9 rows over 10x10cm.