The value for MAX_CURVELIST of 28 in t1_lib.c is too small to support listing all the available curves.

This works:

$ openssl s_client -curves sect163k1:sect163r1:sect163r2:sect193r1:sect193r2:sect233k1:sect233r1:sect239k1:sect283k1:sect283r1:sect409k1:sect409r1:sect571k1:sect571r1:secp160k1:secp160r1:secp160r2:secp192k1:prime192v1:secp224k1:secp224r1:secp256k1:prime256v1:secp384r1:secp521r1:brainpoolP256r1:brainpoolP384r1:brainpoolP512r1 [...]

But this does not, because it has 29 curves:

$ openssl s_client -curves sect163k1:sect163r1:sect163r2:sect193r1:sect193r2:sect233k1:sect233r1:sect239k1:sect283k1:sect283r1:sect409k1:sect409r1:sect571k1:sect571r1:secp160k1:secp160r1:secp160r2:secp192k1:prime192v1:secp224k1:secp224r1:secp256k1:prime256v1:secp384r1:secp521r1:brainpoolP256r1:brainpoolP384r1:brainpoolP512r1:X25519 [...]