Floating Viewport (Paperspace / Layout) automatically Zoom Extents when made active
Floating Viewport (Paperspace / Layout) automatically Zoom Extents when made active, the most likely reason for this behaviour is the current settings of system variable UCSFollow & UCSVP.
Below is taken directly from the AutoCAD Online Help File [F1] -
UCSFOLLOW System Variable
Type: Integer
Saved in: Drawing (viewport specific)
Initial value: 0
Generates a plan view whenever you change from one UCS to another. Set UCSFOLLOW separately for each viewport. If UCSFOLLOW is on for a particular viewport, AutoCAD generates a plan view in that viewport whenever you change coordinate systems. Once the new UCS has been established, you can use DVIEW, PLAN, VIEW, or VPOINT to change the view of the drawing. It will change to a plan view again the next time you change coordinate systems.
0 UCS does not affect the view
1 Any UCS change causes a change to the plan view of the new UCS in the current viewport
The setting of UCSFOLLOW is maintained separately for paper space and model space and can be accessed in either, but the setting is ignored while in paper space (it is always treated as if set to 0). Although you can define a non-world UCS in paper space, the view remains in plan view to the world coordinate system.
&
UCSVP System Variable [ Not available in AutoCAD LT. See THIS post and THIS one. ]
Type: Integer
Saved in: Drawing (viewport specific)
Initial value: 1
Determines whether the UCS in viewports remains fixed or changes to reflect the UCS of the current viewport.
0 Unlocked; UCS reflects the UCS of the current viewport
1 Locked; UCS stored in viewport, and is independent of the UCS of the current viewport
Links:
Autodesk Knowledge Base:
ID: TS41956 - Viewports in model space regenerate unexpectedly
ID: TS21539 - View resets to plan view after a UCS change
ID: TS61919 - When selecting a viewport, view zooms to extents
AUGI Forum:
regen issues
UCS problems?
Viewport resizing when switching between ms/ps?
mvsetup
VIEWPORTS AUTOMATICALLY ZOOM EXTENTS
Viewports zooming extents
Model Tab Zoom Variable?
Viewport regeneration error
Floating Viewport automatically re-scales
Auto Zoom Extents when I enter Modelspace
Floating viewport automatic zoom extents
viewport scaling problem
Viewport Issue - Zoom Extents
VPMAX - Double click inside viewport, maximizes...
Variable to stop viewports from zooming to extents
UCS Object automatically twists background
Viewports in Layouts automatically Zoom Extents
Views within viewports automatically Zoom All
Automatically Zooming in Viewports
DWG does not automatically rotate when setting a new UCS
AutoCAD LT 2006 - Viewport scale changes as I switch between viewports
Regeneration of floating viewports to zoom extents
Viewport goes to extents regardless of scaling when made active
Switch from Modelspace to Paperspace causes Viewport to Zoom Extents?
Zoom extents automatically when you activate a viewport
Viewport zoom extents when made active
