DAQ does not recognize vendor but vendor is listed as operational

I am trying to connect to an NI USB-6001 DAQ. I've got MATLAB 9.7.0.1216025 (R2019b, Update 1) and Data Acquisition Toolbox 4.0.1 (2019b). I have NI's DAQ-MX installed and I have previously been able to connect to my DAQ. The blue light is solid on the USB-6001, indicating that it is connected and there are no issues.

I run the following code:

daqreset
daq.getVendors

and I get an error message:

Error using CIVE123_ACPhaseExploration (line 2)
Vendor 'ni' not recognized. Use 'daq.getVendors()' for a list of
vendors.

Caused by:
    Vendor 'ni' is not operational.
    Use 'daq.getVendors()' for a list of supported vendors.
    Support for the vendor may require installation of the driver via
    the Support Package Installer.
    

However, if I run

    daq.getVendors

I get the message:

    >> daq.getVendors

ans = 

Data acquisition vendor 'National Instruments(TM)':

            ID: 'ni'
      FullName: 'National Instruments(TM)'
AdaptorVersion: '4.0.1 (R2019b)'
 DriverVersion: '19.5.0 NI-DAQmx'
 IsOperational: true

I've shut down and re-opened MATLAB and tried again but it has not fixed it. It appears that 'ni' devices are in fact operational and that the driver is installed. Why does the data acquisition toolbox disagree, and how can I fix it?

[Michael Stachowsky]

Ah, of course what I forgot to do was restart the computer and now it works. However, I'd still like to know what the problem was so that I can potentially avoid it without a restart. Why did the vendor list itself as operational but the getDevices did not?