Create React App - fails to map stack trace

[freemaths]

Attempting to log and debug live errors on a site generated by create-react-app.
The gps object created with new StackTraceGPS() looks to be fine (sourceCache and sourceMapConsumerCache promises are fulfilled).
When using pinpoint it just returns original line and column with an added name of w:

source: main.c8f4e493.chunk.js line: 1 column 255531
source: /static/js/main.c8f4e493.chunk.js line: 1 column 255531 name: w
source: main.c8f4e493.chunk.js line: 1 column 6959
source: /static/js/main.c8f4e493.chunk.js line: 1 column 6959 name: w
source: main.c8f4e493.chunk.js line: 1 column 318036
source: /static/js/main.c8f4e493.chunk.js line: 1 column 318036 name: w

Any suggestions?