As you are probably aware, Maine recently enacted IRV for state elections. As you are also probably aware, Susan Collins voted for Brett Kavanaugh, and in the process made a few enemies. A lot of people will want to run for her seat in 2020. So the 2020 Senate race in Maine will probably be the first IRV election of national importance.
A lot of people in politics, whether they are candidates or activists, do not understand that IRV still has a spoiler effect. So many of the people who want to challenge Collins may well do so, thinking they have nothing to lose.
Since IRV has an extremist bias, if the final field is something like Collins plus 5 left-wing/left-leaning activists and politicians, it’s likely that Collins will draw one of the further left challengers in the runoff. Ironically, the more moderate challengers would probably have better pairwise results against Collins. So there’s a chance that the very first time IRV is on the national stage, it behaves pathologically.
On the other hand, with all the money the Dem nominee will race, the race will probably just consolidate around the two major-party candidates like every other election in this country, preventing any strange behavior. Of course, probably isn’t good enough. (Also, that might just mean IRV screws up in the primary instead of the general, which might be less embarrassing, but isn’t any better.)