I own four devices 2x CSS326-24G-2S+ and 2x CRS317-1G-16S+ and I would like to connect all to assure redundancy.

Both CRS317-1G-16S+ are connected to etch other through port SFP16 both 1GB ports are connected to Cisco router C896SFP where STP is enabled.

I've connect first CSS326-24G-2S+ (aSW1) using SFP1 to first CRS317-1G-16S+ (dSW1) port SFP15
I've connect second CSS326-24G-2S+ (aSW2) using SFP1 to first CRS317-1G-16S+ (dSW2) port SFP15

Until now all is fine. One port is blocked at Cisco router by STP.

When I connect:
aSW1 using port SFP2 to port SFP2 on aSW2
or
aSW1 using port SFP2 to port SFP14 on dSW2
or
aSW2 using port SFP2 to port SFP14 on dSW1
all devices become unavailable.

Please look on attached schemas illustrating desired topology.
Also attached RSTP configuration from SwOS.

Of course RSTP is enabled on all ports used for connection.

Bridge Priority value at Cisco is default - 8000 hex.

All Microtik devices running latest SwOS 2.8.
Mikrotik SFP+ 1m cables are used.

THX in advance for any help.

Two of your pictures show no RSTP enabled on any ports, did you maybe forget to scroll down? Or are you just showing that there is no RSTP enabled on those at all?

Do you have any VLANs configured?

Your diagram and pictures aren't much help since you don't say what is what really in them.
Your post is very messy and I can't figure out what you are trying to say before I get annoyed.