WARNING - SKIPPING VARIANT about INS

[dxkeac]

Hi,there is a problem about svviz2 in processing INS:
svviz2.io.vcfparser - WARNING - SKIPPING VARIANT: chr1 90337 2 N TTGGAGGGAAGGACAGTCCTCTTGTCCCTCTGTCTCTTCCACACAGTTAACTGCGCT 63 PASS SUPP=1;SUPP_VEC=10;SVLEN=93;SVTYPE=INS;SVMETHOD=SURVIVOR1.0.7;CHR2=chr1;END=90410;CIPOS=0,0;CIEND=0,0;STRANDS=+-

Could you help me explain this problem? Is there a problem with the vcf format or the svviz2 can't handle INS?
Your help is greatly appreciated!