e-tron will not start off in EV mode on cold morning

[jetron]

I'd be interested if any of our members, especially those from colder climates, have encountered a similar issue to the following.

I was unable to start off in EV mode one morning. The temperature in the garage was about +5°C while outside was about -2°C. An indicator lamp in the instrument cluster indicated that "e-tron mode: EV mode currently unavailable" because "the conditions for electric driving are not fulfilled", according to the owners manual. It also stated:

Conditions for electric driving

• The high voltage battery must be sufficiently charged
• The high voltage battery must be at an appropriate temperature (not below approx.. -10°C
• The vehicle must not be travelling faster than approx.. 130 km/h
• The kick-down feature must not be used
• The selector lever must not be in the S position

None of these was applicable in my case, but then I noticed a note containing additional information:

Note

For technical reasons, for instance if there is a build-up of condensation in the engine, the combustion engine may need to run for a longer period. During this phase it is not possible to drive on electric power alone.​

I am assuming the latter was my problem as EV mode became available after driving for a few minutes.