Co-site 5G to 4G HO Prep 100% failure

Hi Experts,

What are the possible reasons for 5G to 4G co-site HO Prep 100% failure ?
///E system.

The site is in a remote location, with very limited satellite backhaul.
1 4G layer + 2 5G layers.

AMF and MME status are ENABLED.
Both termpointEnb and Gnb are ENABLED.

Freqrelation bothways are defined.

Thanks