Your Recovery Services vault needs to be in the same region as your workloads unless you are setting up Azure Site Recovery (which based on the RSV name sounds like it).
"Region: Select the geographic region for the vault. For you to create a vault to help protect any data source, the vault must be in the same region as the data source."
Create and configure a Recovery Services vault
If this is true:
Check your scope in the main file, to make sure it's not restricted to RG (so it can't see others) Scope (Scope functions for Bicep) and whether this is set at Subscriptions and what errors are you getting?
I just tested with the below and was able to reference my RSV:
targetScope = 'subscription'
resource rsv 'Microsoft.RecoveryServices/vaults@2023-04-01' existing = {
name: 'prod-rsv-aue'
scope: rg
}
resource rg 'Microsoft.Resources/resourceGroups@2022-09-01' existing = {
name: 'backuprsv-prod'
scope: subscription()
}
output test string = rsv.properties.redundancySettings.crossRegionRestore