Instant preview: different sizes in different situations

[Rudi Gaelzer]

Using:
LyX v. 2.3.6.1
OS: Fedora Core 33
TeXLive v. 9

I noticed a weird behaviour for some time already with Instant Preview.
In: Preferences -> Look & Feel -> Display -> Instant preview, 
if I set Preview size 1.2, then during the edition, when a given formula is 
rendered for the first time, the display size is OK.
However, when I restart LyX and resume processing the text, the same formula 
is rendered with a much smaller size... very difficult to read.

If I try to circumvent this problem by setting preview size to, say,  1.5, 
then on the first time the equation becomes huge, although after restart the 
new size is better than with the previous setting.

Has anyone noticed this behaviour as well?  I'd say this is a bug, but, I 
don't know...

-- 
Rudi Gaelzer
Instituto de Física
Departamento de Física
Universidade Federal do Rio Grande do Sul