How to reproduce the behaviour

I use the doccano 1.3.1 from here and setup with Python and Node.js.

When I create a project and injest data, whatever format I select, it show the rings keep spinning

The data is from the tutorial and save as json format.

and the log of backend is keeping repeat the last line of following sample log:

[10/May/2021 22:10:39] "POST /v1/projects/2/upload HTTP/1.1" 200 50
[10/May/2021 22:10:42] "GET /v1/tasks/status/e881360a-1a17-436b-ba7b-aa0d8c9845c3 HTTP/1.1" 200 42
[10/May/2021 22:10:45] "GET /v1/tasks/status/e881360a-1a17-436b-ba7b-aa0d8c9845c3 HTTP/1.1" 200 42
[10/May/2021 22:10:48] "GET /v1/tasks/status/e881360a-1a17-436b-ba7b-aa0d8c9845c3 HTTP/1.1" 200 42
[10/May/2021 22:10:51] "GET /v1/tasks/status/e881360a-1a17-436b-ba7b-aa0d8c9845c3 HTTP/1.1" 200 42

• Operating System: Win10 x64
• Python Version Used: 3.9.5
• When you install doccano: today
• How did you install doccano (Heroku button etc): python+node.js 14.16.1