The leaderboard wipe won't impact any local saves.
In a post today, Harmonix announced that the company will be wiping the leaderboard scores in Rock Band 4 for all songs after identifying a "gnarly bug." The exploit allowed for drummers to double trigger overdrive.
"Rock Band 4 shipped with a handful of gnarly bugs, including an issue where experienced drummers can double-deploy overdrive by hitting the green 'Overdrive' gems at the end of dynamic drum fills," the post reads. "But with your help, we've identified (and are fixing) potential score exploits that compromise the integrity of our leaderboards."
The plan to fix this issue comes in three waves: first, Harmonix will fix the issue. Second, they will wipe all of the leaderboard scores for all songs. "Why? Because we're making improvements that affect almost every song, instrument, and difficulty in the game," the post explains. The leaderboard wipe won't impact any local saves. The third step in the plan involves an adjustment to the game's code that will allow the developers to address song-specific bugs and issue "targeted leaderboard wipes."
"We know that many of you have worked hard to climb the leaderboards, and that wiping your scores sucks," the post continues. "That said, these changes will ensure that in the future, you won't be unseated from the top spot by someone using an exploit. And if we do discover an issue down the road, we can address it much more quickly and easily."