LED tubes are technically electronic devices. Flashing indicates that there is an incompatibility somewhere in the application. Shutting off after working for any period of time and failing to come back on also indicates incompatibility.
In the vast majority of cases, LED tubes flashing or turning off mean that they are not ballast compatible. In this case, we recommend doing a simple ballast bypass and wiring your tubes directly in the fixture. This should immediately improve performance and energy savings.