Mixed up reads within bam file

[jsikora93]

Hi,
I visualized of BAM file in IGV. For IGV, I set up of "group alignments by first-in-pair starnd" and "color alignments by read strand". I do not know why I had both reads from positive and negative strand within track for negative or positive first-in-pair strand. I attached of file with IGV visualizations. I would like to ask that my reads are proper alignment?
Reads group by positive or negative first-in-pair strand.pdf

I will be grateful for help.
Regards,
Jarek