I just upgraded to 8.4(5) and seeing the same issue with NTA. Found Cisco blog that talks about it: Cisco ASA 8.4.5 NetFlow issue|2183526 - Cisco Support Community
8.4(5) includes enhanced NetFlow capabiities. Guess we have to wait for SW to update NTA.
FYI - opened support case# 411143 for this issue.
NTA Hotfix 3 is available. Installed it this morning and now getting flows from my ASA running 8.4(5). Thanks to Brian at Solarwinds support for a quick solution!