I think Rudy's on-court value is high for a lot of teams, not just the Jazz. I think teams are waiting to see how Rudy's market plays out. They're not going to make their best offer until they know what other teams are offering and what they have to bid against. Also, if draft picks are involved in the trade discussion, the team will weigh the trade against other offers for their picks. Rudy's market is also complicated by other factors like Deandre Ayton, what on earth is going on in Brooklyn, which teams Zach Lavine is leaning towards, what Portland is going to do with the #7 pick, etc.
By the time of the draft, it should be clear whether the Jazz are likely to move Gobert or not. Two days before the draft, a team like Charlotte might say, "Okay, we'll do Rozier, Washington and our first-round picks for Gobert." They won't be pressed to decide sooner than that.
The hope is that a couple teams, like Atlanta and Charlotte, come to the conclusion that trading for Rudy is their best route to improving, so they make a strong move and the market heats up. I think that's plausible. If not, that sucks, tbh.