I can not see the intron region aligned to ref in IGV from ONT direct RNA sequencing

Question

[Zhen]

I want to see the splicing of my vector/reporter, after plasmid transfection and RNA extraction, I run the ONT direct RNA sequencing, I got the raw FASTQ file from Minion1B, and using minimap2 mapping to my reporter plasmid fasta file. After convert into sorted bam file, I loaded them into IGV, but I can not see the intron region.