Yeah that Pz IV model switch is caused by the SP 1.4 mod Peter
For some reason when they did the SP 1.4 mod they made the PzIV F1 model the tank for the first 2 or 3 missions of the campaign, after those missions I do believe you get the PzIV F2 back. I agree with you also I have no love for the PzIV F1 either, wish they would have just left the well enough alone on that one
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The Unofficial Mod has no bearing on this PzIV model switch as it only addressed some localization errors and a few game bugs. I'm not even sure you need it if your using the SP 1.4 mod. My understanding is the SP mods were cumulative, so when you activate SP 1.4 your also getting all of the previous SP mods back to SP 1.0 which I think included the Unoffical Patch (could be wrong on this one). Just so there is no confusion Pete in my other posts about activating the Unofficial Patch last in JSGME was only because the latest mods coming from the RU (like Tiger Mod 0.98) changed the English game user interface to Russian. By activating the Unofficial Mod last it changed the game user interface back to English.
P.S. You could try installing the previous SP 1.3 mod instead of SP 1.4, that would get you your PzIV F2's back but you would be giving up anything new or improved that was added in SP 1.4. I would compare both SP 1.3 and SP 1.4 read me text and see if rolling back would be a viable option for you.