Given that there are 6 x 5 white blocks, and the linear nature of the motif, I decided to quilt this motif on alternating white blocks and maybe use a wreath type motif on the other white blocks. This would help to disguise any wonkiness in my quilting the first motif as I wouldn't have to line everything up perfectly.
As the quilting is nowhere near finished, I tried to spot remove it, to no avail.
I decided to try and hide it by quilting over it and I've now almost completed two rows. Here are pictures of the quilted motifs. I'm going to have to try and find another method for marking motifs without a template, as I just can't run the risk of this happening again. I had the same problem on a section of the border of my mother's quilt.