If you are sure this is a bug you have to reproduce it and there is the only way to convince your dev mate that the application code has a defect. Here is some advice on that:

• Consider the execution environment specific. Whether there was anything remarkable. Probably there was a midnight, or you took your device in a certain position or there was low battery level or there was broken mobile data channel or some blue-tooth devices connected, etc.
• Consider the external service. What services does you app use. Were there any maintenance activities on those services. If all the external services are mocked what was the mock configuration.
• Check if the app produces log at either your device or some remote log collector
• Check the log of server components which your app work with
• Ask your dev mate for help. Describe them the app behavior that you observed in the maximum level of details. Localize the area in the code that could handle that behavior and watch the particular code parts to figure out what potentially could lead to that behavior.

P.S. - Here is also some post that is worth reading for those who faces the "strange" and hardly-reproducible defects.

If you are sure this is a bug you have to reproduce it and there is the only way to convince your dev mate that the application code has a defect. Here is some advice on that:

• Consider the execution environment specific. Whether there was anything remarkable. Probably there was a midnight, or you took your device in a certain position or there was low battery level or there was broken mobile data channel or some blue-tooth devices connected, etc.
• Consider the external service. What services does you app use. Were there any maintenance activities on those services. If all the external services are mocked what was the mock configuration.
• Check if the app produces log at either your device or some remote log collector
• Check the log of server components which your app work with
• Ask your dev mate for help. Describe them the app behavior that you observed in the maximum level of details. Localize the area in the code that could handle that behavior and watch the particular code parts to figure out what potentially could lead to that behavior.

P.S. - Here is also some post that is worth reading for those who faces the "strange" and hardly-reproducible defects.

If you are sure this is a bug you have to reproduce it and there is the only way to convince your dev mate that the application code has a defect. Here is some advice on that:

• Consider the execution environment specific. Whether there was anything remarkable. Probably there was a midnight, or you took your device in a certain position or there was low battery level or there was broken mobile data channel or some blue-tooth devices connected, etc.
• Consider the external service. What services does you app use. Were there any maintenance activities on those services. If all the external services are mocked what was the mock configuration.
• Check if the app produces log at either your device or some remote log collector
• Check the log of server components which your app work with
• Ask your dev mate for help. Describe them the app behavior that you observed in the maximum level of details. Localize the area in the code that could handle that behavior and watch the particular code parts to figure out what potentially could lead to that behavior.

If you are sure this is a bug you have to reproduce it and there is the only way to convince your dev mate that the application code has a defect. Here is some advice on that:

• Consider the execution environment specific. Whether there was anything remarkable. Probably there was a midnight, or you took your device in a certain position or there was low battery level or there was broken mobile data channel or some blue-tooth devices connected, etc.
• Consider the external service. What services does you app use. Were there any maintenance activities on those services. If all the external services are mocked what was the mock configuration.
• Check if the app produces log at either your device or some remote log collector
• Check the log of server components which your app work with
• Ask your dev mate for help. Describe them the app behavior that you observed in the maximum level of details. Localize the area in the code that could handle that behavior and watch the particular code parts to figure out what potentially could lead to that behavior.

P.S. - Here is also some post that is worth reading for those who faces the "strange" and hardly-reproducible defects.