Uncertain behavior after configuring NAT in Mikrotik-750GL router, sometimes works sometimes not ?

Hi,

I connected 4 PCs with the help of router and configuring NAT
below is PC configuration.

L-PC: 192.168.11.11/24 Default Getaway: 192.168.11.1
Device-01: 192.168.0.72/24 Default Getaway: 192.168.0.1

R-PC: 192.168.22.22/24 Default Getaway: 192.168.22.1
Device-02: 192.168.0.138/24 Default Getaway: 192.168.0.2

Attaching the image for router configuration.
NAT_Config.JPG
Device-01 and device-02 are on same network and I want to configure a network in such a way that L-PC should communicate only with Device-01 and R-PC with Device-02. For that I added NAT rules as shown in image.

After configuration it work as expected but not every time. Sometime doesn’t connect ie L-PC not able to communicate with Device-01 when try to ping it says destination host unreachable and at the same time R-PC can ping to Device-02.
Also sometimes connection lost after few minutes

So am no able to trace why it is behaving like this could you please help me.

Thanks..