wekan: Missing images after big Import from Trello

Issue

Server Setup Information:

• Wekan version: 4.13
• Operating System: Ubuntu 16.04
• Deployment Method: Docker
• Http frontend: Nginx Reverse Proxy (Jwilder)
• Node Version: 12.18.0
• MongoDB Version: 4.2.7
• What webbrowser version are you using? Firefox Problem description:

• Missing images after importing a board from Trello
• I import the Trello board with Json export / Import. After a while the board appears in Wekan, but some, not all Images are missing

** Docker-compose file**:

version: '2'


services:

  wekandb:
    image: mongo:latest
    container_name: wekan-db
    restart: always
    command: mongod --oplogSize 128
    networks:
      - wekan-tier
    expose:
      - 27017
    volumes:
      - wekan-db:/data/db
      - wekan-db-dump:/dump

  wekan:
    image: wekanteam/wekan
    container_name: wekan-app
    restart: always
    expose:
      - "8080"
    networks:
      - wekan-tier
      - default
    environment:
      - MONGO_URL=mongodb://wekandb:27017/wekan
      - VIRTUAL_HOST=boards.*****
      - LETSENCRYPT_HOST=boards.******
      - LETSENCRYPT_EMAIL=admin@****
      - VIRTUAL_PORT=8080
      - ROOT_URL=https://boards.****  #   <=== using only at same laptop/desktop where Wekan is installed
      - MAIL_URL='smtp://<mail_url>:25/?ignoreTLS=true&tls={rejectUnauthorized:false}'
      - MAIL_FROM='Wekan Notifications <noreply.wekan@mydomain.com>'
      - WITH_API=true
      - OAUTH2_ENABLED=true
      - OAUTH2_LOGIN_STYLE=redirect
      - OAUTH2_CLIENT_ID=****
      - OAUTH2_SECRET=****
      - OAUTH2_SERVER_URL=https://files.****
      - OAUTH2_AUTH_ENDPOINT=/index.php/apps/oauth2/authorize
      - OAUTH2_USERINFO_ENDPOINT=/ocs/v2.php/cloud/user?format=json
      - OAUTH2_TOKEN_ENDPOINT=/index.php/apps/oauth2/api/v1/token
      - OAUTH2_ID_MAP=id
      - OAUTH2_USERNAME_MAP=id
      - OAUTH2_FULLNAME_MAP=display-name
      - OAUTH2_EMAIL_MAP=email
      - BROWSER_POLICY_ENABLED=true

    depends_on:
      - wekandb

volumes:
  wekan-db:
    driver: local
  wekan-db-dump:
    driver: local

networks:
  default:
    external:
      name: webproxy
  wekan-tier:
    driver: bridge

** Nginx VHost Config for Jwilder**:

        ##
        # Basic Settings
        ##

        ## Max attachment size that can be uploaded to Wekan:
        client_max_body_size 1000M;
        sendfile on;
        tcp_nopush on;
        tcp_nodelay on;
        types_hash_max_size 2048;
        server_tokens off;
        set_real_ip_from 0.0.0.0/32; # All addresses get a real IP.
        real_ip_header X-Forwarded-For;
        client_body_timeout 60;
        client_header_timeout 60;
        keepalive_timeout 10 10;
        send_timeout 60;
        reset_timedout_connection on;

        # server_names_hash_bucket_size 64;
        # server_name_in_redirect off;

        include /etc/nginx/mime.types;
        default_type application/octet-stream;

        ##
        # SSL Settings
        ##


        ##
        # Logging Settings
        ##

        access_log /var/log/nginx/access.log;
        error_log /var/log/nginx/error.log;

        ##
        # Gzip Settings
        ##

        gzip on;
        gzip_disable "msie6";
        gzip_buffers 16 8k;
        gzip_comp_level 1;
        gzip_http_version 1.1;
        gzip_min_length 10;
        gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript image/x-icon application/vnd.ms-fontobject font/opentype application/x-font-ttf;
        gzip_vary on;
        gzip_proxied any; # Compression for all requests.