Version 2.4.0~RC4 Instant preview stops working when inserting floats or comments

[fcanatay at gmail.com]

>>> Alternatively, are you able to run LyX from a terminal in order to have other error messages ?
>> Running LyX from terminal I got the following:
>> 
>> qt.qpa.fonts: Populating font family aliases took 163 ms. Replace uses of missing font family "Serif" with one that exists to avoid this cost.
>> Warning: Failed: dvips lyxpreviewZhflDz.dvi ... looking for PDF
>> Error: Failed to extract metrics info from lyxpreviewZhflDz.log
> 
> Something is wrong here. The "Failed" warning is why the preview is failing. Try running:
> 
>     lyx -dbg graphics
> 
> and see if you get more information. You can also open the messages pane and then under "Settings" in that window activate graphics debug info.
> 
> Riki
> 

This is the error line in Messages Pane with graphics debug info:

graphics/PreviewLoader.cpp (246): PreviewLoader::startLoading()
graphics/PreviewLoader.cpp (2f0): PreviewLoader::finishedInProgress(1): processing failed for python3 -tt $$s/scripts/lyxpreview2bitmap.py --png "/private/var/folders/49/yb2413c16tn4y7gqpr1pwm5c0000gn/T/lyx_tmpdir.kZdswlpFtuiy/lyx_tmpbuf1/lyxpreviewydILJu.tex" --dpi 272 --fg 000000 --bg ffffff --bibtex=“bibtex”