ECDSA Cipher help on LTM

Hello f5 experts,

I am trying to add below cipher to a SSL profile but the customer is not able to see it on SSLlabs, I checked few solutions and tried adding it but the ECDSA part is missing. Can someone please help me enable it? f5 version we use is - 11.5.5

TLS_ECDHE_ECDSA_WITH_AES_128_GCM_

Thanks, R