Android AAC-HE encoder initialization fails with 8khz sampling rate

I am trying to initialize AAC encoder with the following parameters aac-profile=5, mime=audio/mp4a-latm, bitrate=12000, channel-count=1, sample-rate=8000

But the codec initialization fails with the following error:

06-14 19:17:58.009 6194-6450/? E/SoftAACEncoder2: Unable to initialize encoder for profile / sample-rate / bit-rate / channels
06-14 19:17:58.010 6194-6449/? E/ACodec: [OMX.google.aac.encoder] ERROR(0x80001001)
06-14 19:17:58.010 6194-6449/? E/ACodec: signalError(omxError 0x80001001, internalError -2147483648)
06-14 19:17:58.010 6194-6449/? E/MediaCodec: Codec reported err 0x80001001, actionCode 0, while in state 6

But, when I try to initialize it with sampling rate of 16khz, it works, but the documentation says, the AAC-HE profile supports 8khz sampling rate. Any idea what could be the issue?