When I look at the source code, I’m seeing 0 elements in each filter when the search override is activated. Maybe that is the reason why it’s “hidden”, as it thinks that there is nothing to filter. I guess the other plugin can’t see the results, or is trying to fetch the original query, which no longer exists as it’s been overridden. I have checked and all filter elements say that there is 0 items, so this is probably the issue and the filter simply hides itself.
The only way to solve it and use both plugins at the same time is to turn off the search override.