When a “scheduled update” is applied to an operating system image, it uses the C: drive by default. It stores a copy of the WIM fil in C:\ConfigMgr_OfflineImageServicing. Needless to say, this might not be where you want it. You can change the location by editing the WIM data to reflect the new drive letter.
**Note: this assumes the sitename is PS1
Connect button: ROOT\SMS\SITE_PS1 namespace
SELECT * FROM SMS_SCI_Component WHERE FileType=2 AND ItemName='SMS_OFFLINE_SERVICING_MANAGER|SMS Site Server' AND ItemType='Component' AND SiteCode='PS1'
Results are displayed: 1 object
Double-click the resulting line: object editor window opens
Scroll to find PROPS in the Properties column.
Double-click it to open Property Editor
Click View Embedded
Double click each one, and find the one that has a PropertyName equal to StagingDrive. Mine had it in the second EmbeddedProperty line.
Edit the value, changing the dirv eletter as shown.
Save the property, and close all the windows, saving along the way.
It should take effect the next time you apply updates.