Hi,
It looks like it may be something to do with how Bitnami handles the environment.
I'm currently testing on a Bitnami server I just spun up and will report back shortly.
I was able to get the database to backup by changing the wp-config from Bitnami's default host of 'localhost:3306' to just 'localhost'. Fair warning- I'm not sure if Bitnami added the port to the default WordPress database host for a particular reason, so I'm not sure if changing that would affect any of their other services. 3306 is the default port though.
Looking into the other issue you're having and will keep you posted on my findings.