Fire Fox does not count table rows in NVDA Screen Reader, but does in Chrome

I am trying to make an accessible expandable table (taking this as inspiration: https://fuschia-stretch.glitch.me/ , check out “View souce”), but the NVDA screen reader do not read the number of columns in Fire Fox, but reads them in Chrome. Here are some examples:

// It seems like it is this block that is causing it to not count in Fire Fox, but it counts in Chrome, what can the reason be? Or how to solve this?
tr {
  display: flex;
  flex-flow: row wrap;
}

Thank you for all help