Although AccuSnap is enabled, snapping the cursor does not work when placing a fence.
Both solution options listed below can work in v8i & CONNECT versions of MicroStation.
Active the Place Fence tool, then press and hold the CTRL+ SHIFT keys at the same time, then place the fence.You can release the keys after finishing the fence placement.This will not permanently affect AccuSnap settings.
In MicroStation v8i, navigate to Settings menu > Snaps > AccuSnap
In CONNECT, click the dialog launcher contained in Drawing workflow > Drawing Aids tab> Snaps Ribbon Group
Alternatively, in v8i, you can select the AccuSnap icon in the status bar then click AccuSnap:then select the General tab > and toggle ON Enable For Fence Create then exit the dialog.
Similarly, in CONNECT, select the Snaps icon at the bottom of the interface and click on the dialog launcher:
Then toggle ON Enable For Fence Create and then exit the dialog.
Be sure to save settings (CTRL+f) to keep these changes for future sessions of MicroStation.
AccuSnap Settings - MicroStation CE Online Help