This happens randomly in my games every so often (probably every half-hour to hour on average, although I had a shocking run yesterday where it kicked in within five minutes of restarting twice in a row!).  Not sure what's driving it, that part of the tooltip just drops off, and isn't fixed without a game restart.

i personally think the biggest driver in this issue is techs or events that change ship stats.

this tech gives you +10 % moves .....   reset tooltip

this event gives you +3 sensor radius    ..... reset tooltip

you just upgraded this ship     ...... reset tooltip