Hi Joao,
Please see the following:
Troubleshoot error: "Azure Functions Runtime is unreachable"
https://learn.microsoft.com/en-us/azure/azure-functions/functions-recover-storage-account
Monitor executions in Azure Functions
Azure Functions offers built-in integration with Azure Application Insights to monitor functions executions. This article provides an overview of the monitoring capabilities provided by Azure for monitoring Azure Functions.
https://learn.microsoft.com/en-us/azure/azure-functions/functions-monitoring
With the two above, you should be able to figure out a more in-depth analysis of why your Function is having troubles.
If this is helpful please accept answer.