Grafana for CloudWatch not working after 5.0.0

I am using Grafana on premise on a Windows 2008 R2 Enterprise OS. Data source = CloudWatch and it works just fine.

Just downloaded Grafana 5.1.3 and I can’t seem to connect to CloudWatch using the SAME credentials that are working on 5.0.0 (on the same machine). In the logs I see:

t=2018-05-22T09:06:43+0000 lvl=info msg="Initializing HTTP Server" logger=http.server address= protocol=http subUrl= socket=
t=2018-05-22T09:06:57+0000 lvl=eror msg="Metric request error" logger=context userId=1 orgId=1 uname=admin error="Failed to call cloudwatch:ListMetrics, RequestError: send request failed\ncaused by: Post proxyconnect tcp: tls: oversized record received with length 20527"

The installation (unzip) is clean and has NOTHING configured except for a custom.ini that sets ports and hostname. Does anyone else face this issue? Seems to be a bug with the later versions of Grafana all else being same.

I am behind a corporate proxy and I startup grafana with a batch file (that works fine in 5.0.0):

cd F:\Apps\\grafana-5.1.3\bin
set https_proxy=
set http_proxy=

Created an issue