Photoshop CC 23.1.1 (and other versions, as discussed)
Related or the same bugs have been reported on this forum before, but this is happening to me even on old versions, so may not be the same. I have tried to be thorough and give context so it is unambiguous what I'm saying is happening. Also I threw in a few related bugs discovered during the process of characterizing this accurately.
(1) Smart Portrait will only run successfuly once without restarting Photoshop.
"Neural Filters" launches a modal dialog in which you can select Smart Portrait, which opens a pane with a number of sliders. The first time you touch a slider, PS reports "Processing on the cloud" and gives you a progress bar. Then, when you tweak the sliders, it informs you that it's running the processing locally. I can tweak the sliders to my heart's content. I can then click "Okay" and the filtered data is output to a layer. This is all working as expected.
If I then try to run Neural Filter -> Smart Portrait again, then the first time I touch a slider, PS informs me it's processing in the cloud, but it then produces an error message (after the progress bar has only reached about 20%):
"We've temporarily disabled this filter because of an error."
Dragging the sliders around at this point produces the same error. Exiting Photoshop and restarting it fixes it, but starts the process over: it allows Smart Portrait to be used successfully once, and then further attempts get the same error.
I tried this in the following versions of Photoshop CC and had the same results in all four: 23.1.1 23.1 23.0.1 22.5.5
I also tried disabling GPU hardware acceleration and it did not affect the bug.
As an exception, after the first successful Smart Portrait step, I could repeat the filter with Alt-Shift-F without error. For example, I used Smart Portrait to change the eye direction, and then each time I prssed Alt-Shift-F, it moved the eye direction further and further, after some processing time. This is the correct, expected behavior. (The fact that this works might be useful for someone technical to help diagnose which part of the pipeline is failing for me.)
(2) Installing the Smart Portrait filter fails consistently on a fresh install of PS.
Smart Portrait is a filter that requires a separate 'installation' step, which it prompts you for when you open it. For me this filter installation *always* fails the first time running Photoshop after an installation. You must exit Photoshop and restart it before it will install. (I tried this with three versions of PS CC and saw the same behavior on all three, I believe I followed the instructions to cleanup the com.adobe.nfp.gallery/PluginData directory to simulate a 'clean install'.)
(3) "We've temporarily disabled this filter because of an error" is an unhelpful message.
This message appears in the scenario described in (1), and probably in other circumstances. The message does not communicate anything actionable to the user. For example, it's a cloud service, so it could imply that that there is a network error, and that the user should expect it to start working again spontaneously. However, in my case, the error is *not* temporary. It appears I could try repeatedly for hours or days and it would never start working again unless I closed the program and restarted it; but "we've temporarily disabled" does not communicate this in any way.
Since the message does not directly communicate anything actionable to the user, the only other thing the user can do is search for the message on the Internet. Unfortunately the Internet is full of out-of-date messages telling people to upgrade to 23.0.1 to fix some bug that triggered the message, which is not very helpful now (though I did try that version for completeness).