The SZ-H documents do not do mention about the maximum amount of clients that you can block by selecting a client and then the option block.
Might you be referring to block clients using L2/L3 ACLs?
Kindly share some more details or whether there is any issue that is been faced.
Thank you for clarifying.
For each client that we block, a new line will be created in the L2 filter. Each L2 filter supports a maximum of 128 lines.
Only one L2 filter can be applied per WLAN.
Please let me know if you have additional concerns.