Hi,
My solution is to add the following option at converter definition of Lyx Preview -> PNG in Preferences
python -tt $$s/scripts/lyxpreview2bitmap.py --png
=>
python -tt $$s/scripts/lyxpreview2bitmap.py --png --latex=pdflatex
hope this help
LyX ⇒ Lyx preview: image inside TikZ picture
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