DKS403-M24 KVM Switching Issue Between RTX 5090 and RTX 4060

Hi All,

I am experiencing a switching issue with my DKS403-M24 KVM and would appreciate your assistance.

System Configuration
Computers
PC1: ASUS DUAL-RTX4060-O8G-EVO (3840x2160, 60Hz) Connected to the KVM via 2 × DisplayPort and 1 × USB
PC2: Gigabyte GeForce RTX 5090 WINDFORCE OC 32G (3840x2160, 60Hz) Connected to the KVM via 2 × DisplayPort and 1 × USB
PC3 & PC4 Not connected.

Displays
DisplayPort Output A Connected directly to MSI MPG322URX OLED monitor via DisplayPort 
DisplayPort Output B Connected to Samsung S32BM700UE monitor using a DisplayPort-to-HDMI cable

Steps to Reproduce
1. Power on the KVM and switch to PC1.
2. Power on PC1. Both monitors display normally.
3. Power on PC2 and wait until Windows has completely loaded.
4. Switch the KVM to PC2. Both monitors work normally.
5. Switch the KVM back to PC1.
6. The Samsung monitor continues to work normally. The MSI monitor displays "DP No Signal" and remains blank.

Observations
The issue occurs every time when switching from PC2 (RTX 5090) back to PC1 (RTX 4060).

We have already performed the following tests:
- Swapped all DisplayPort cables.
- Tested every DisplayPort output on both graphics cards.
- Changed the KVM EDID mode (including Pass mode).
- Performed cross-cable testing.
None of the above resolved the issue.

Additional observations:
If the MSI monitor shows "DP No Signal", turning the KVM off, waiting 10 seconds, and turning KVM on, MSI monitor display back to normally.
If the MSI monitor shows "DP No Signal", unplugging the DisplayPort cable from the KVM, waiting 10 seconds, and reconnecting it, MSI monitor display back to normally.
If PC1 is working normally, switching from PC1 → PC3 (or PC4, which are empty inputs) → PC1 works correctly. Both monitors continue to function normally.

This suggests the issue only occurs after switching from the RTX 5090 system back to the RTX 4060 system.

Could you please advise:
Is this a known compatibility issue between the DKS403-M24 and NVIDIA RTX 5090 / RTX 4060 graphics cards?
Is there any firmware update available for the KVM?
Are there any recommended settings or configuration changes to resolve this issue?

Thank you!!