It seems that the reload tasks of the Apps can have issues when uploading the file. In this case the app trying to be reloaded has a size of 1 GB and the tasks used to fail frequently.
By changing the "max retries" (it was set to 0 retries) of the App the issue is solved.
However, I can't understand how the QMC is not able to reload the app at first and needs up to 6 retries...
I get the following error:
Sequence# ProductVersion Timestamp Severity Hostname Id EngineTimestamp EngineVersion Description ProxySessionId ProxyPackageId RequestSequenceId UserDirectory UserId SessionId ObjectId ObjectName Service Origin Context Command Result Message Id2
66 220.127.116.11 20180723T081838.450+0200 ERROR SES000A106688 8d86e6b8-01aa-4752-8f20-d9963727a30c 20180723T081838.459+0200 18.104.22.168 Command=Doc::DoSave;Result=9001;ResultText=Error: Read Failed 0 0 34797 INTERNAL sa_scheduler 1585f367-6507-4e8c-988e-f7acaab0202e 0 Not available Engine Not available Doc::DoSave Doc::DoSave 9001 Could not read app 8d86e6b8-01aa-4752-8f20-d9963727a30c