Confirmed by JetBrains support to be an issue within Rider.
Being addressed via this pull request that missed the 2022.1 release but should be included in the subsequent one.
Although having read through https://learn.microsoft.com/en-gb/azure/azure-functions/create-first-function-cli-csharp?tabs=azure-cli%2Cin-process&pivots=programming-runtime-functions-v4 and the linked articles I have decided to utilise the Azure CLI going forwards for creating & publishing Azure function apps.
Created my function app via:
az functionapp create --resource-group <RESOURCE-GROUP-NAME> --consumption-plan-location <REGION-NAME> --runtime dotnet --functions-version 4 --name <FUNCTION-APP-NAME> --storage-account <STORAGE-ACCOUNT-NAME> --os-type Linux
Published my function app via:
func azure functionapp publish <FUNCTION-APP-NAME>
Also blogged my approach here: https://www.davidbuckell.com/blogs/development/azure/function-apps/creating-linux-net-6-azure-function-apps-via-the-azure-cli/, which I'll tidy up soon.