Happy to inform you that turning off feature called: Enhanced Sync fixes the issue.
How I came to that conclusion? As described on official web page from amd - radeon on link under release notes: Radeon™ Software Adrenalin 2019 Edition 19.8.1 Release Notes | AMD.
You can see following stated:
Known Issues
- Stutter may be experienced when Radeon FreeSync is enabled on 240hz refresh displays with Radeon RX 5700 series graphics products.
- Radeon Performance Metrics may report incorrect VRAM utilization.
- AMD Radeon VII may experience elevated memory clocks at idle or on desktop.
- Radeon Overlay may intermittently fail to appear when toggled in game.
- Audio for clips captured by Radeon ReLive may be corrupted or garbled when desktop recording is enabled.
- Enabling Enhanced Sync may cause game, application or system crashes on Radeon RX 5700 series graphics products.
So, I have disabled Enhanced Sync and my Fortnite was stable last 6-7 hours. No crashed in the menu, while trying to turn it on or mid-game in any game mode. Do not use this until they release something like this:
Fixed Issues
- Some system configurations may experience color corruption after install of Radeon Software when running Windows® 10 May 2019 update. Issue is resolved in the latest Windows® Update 18362.267 (KB4505903)
- Radeon Chill settings may not sync with game profile settings when changed in-game through Radeon Overlay
- Radeon RX 5700 series graphics products may experience a black screen or flickering when applying auto overclocking memory with games or applications running in fullscreen
- Radeon AntiLag may slightly impact performance in select games
- Radeon RX 5700 Series Graphics may experience a black screen during uninstall on Windows®7 system configurations. A work around is to perform uninstall in safe mode.
- Recording clips with Radeon ReLive may result in blank clips on Radeon RX 5700 Series Graphics with Windows®7 system configurations.
Where it will have stated this under fixed issues:
Enabling Enhanced Sync may cause game, application or system crashes on Radeon RX 5700 series graphics products.
Cheers!