Interesting one! Somehow either your fzz file got corrupted or (less likely I think) core parts did. The problem is the fzz file has the wrong moduleId for the PCF8574 and thus can’t load it. I think it is unlikely (although I haven’t checked the git logs for the parts repo to verify that) that core parts changed, but correcting the moduleId makes it work correctly.
In Fritzing load lcd1602_i2c.fzz
Unable to find following part:
'PCF8574 at C:/Program FIles (x86)/fritzing/fritzing-parts/core/PCF8574.fzp
In Fritzing Help->Enable debugging log
debug log indicates the problem is
module id PCF8574 not found in database
but the PCF8574 part in core loads correctly, so the problem isn’t in the part which leaves the fzz file.
so unzip lcd1602_i2c.fzz and edit
to find out what moduleId it is using for the PCF8574, as indicted above it is using PCF8574, but the actual moduleId in the core part is PCF8574A_f92705dc5bbcb278fb8f55ff08c7872a_1 so it looks like that one value in the fz file got truncated somehow (don’t know how). Replacing the original moduleId with the correct one and rezipping the fzz file fixes things:
lcd1602_i2c-fixed.fzz (22.3 KB)