Merely selecting 'Rec" will not record the activity on the scanner. For the non-database DMA scanners, such as the 325P2, the only way to record anything is use the scanner via the 'Control Scanner' option. When the scanner stops on a frequency (or talkgroup) that you have tagged to record, it will record the audio, on your PC, provided that you have an audio patch cable connected, When using the 'Control Scanner feature, you get a settings menu for 'Virtual Control. That has the section where you enable recordings, as well as specify where the recordings should be saved.That sounds completely at odds with this, from earlier in the thread:

See this Wiki page: FreeScan Audio Recording - The RadioReference Wiki
For the 996P2, you can program a channel with record selected. That scanner has a separate "Record Out" jack. Audio is sent to that jack when a channel, tagged for Record. when the scanner is receiving it. You still need an audio patch cable.
The 325P2 does not have a 'Record Out' jack. Audio is only played through the speaker, or via an external speaker (or headphones) when you are controlling scanning & recording via software & virtual control,
For the database scanners, such as the BCDx36HP & SDS series, selective recording still is done on the PC, when the scanner is connected & Virtual Control is in use. In this mode, you are specifying which channels/talkgroups you want recorded, as well as where you want the recordings saved, and you still need a connection between the scanner & PC for the audio (For the SDS200, you could use the LAN connection, instead of a separate audio patch cable. That can be done with ProScan.)
For the database scanners noted above, as well as the HP-1 and HP-2, you can set the scanner to record all activity, with the files saved to the scanner's SD card. But that's recording everything.