A stab in the dark.
Probably way off base.
Is it just this project/file or all?
Could you or someone else (evil twin) been fooling around with the windows registry?
See AC help:
Using the Windows Registry
Some of the basic settings of ArchiCAD are written into the Windows Registry. This Section in the Registry is created by the ArchiCAD Installer program or by the very first start-up of ArchiCAD or PlotMaker under the Key Name: "HKEY_CURRENT_USER\Software\Graphisoft\ArchiCAD" or "HKEY_CURRENT_USER\Software\Graphisoft\ PlotMaker". Every time you run ArchiCAD or PlotMaker the program will read, modify and write back information into the ArchiCAD and PlotMaker registry. If this section is missing, ArchiCAD or PlotMaker will automatically create a new one and save the default settings.
The above ArchiCAD Registry entry contains several subkeys. (Because the ArchiCAD and PlotMaker Registry keys are quite similar, only the ArchiCAD subkeys will be described here). The most important of these are:
Last Started Version: Under this Key Name, you can find the name and version number of the ArchiCAD version that was last started, for example: Last Started Version "ArchiCAD for TeamWork 8.1 INT".
ArchiCAD for TeamWork 8.1 INT (or the ArchiCAD name and version number actually written after the Last Started Version Key Name in the previous section): This section contains (among other information used for internal purposes only) three important Keys: Default TrueType Font, Large Dialog Font and Small Dialog Font.
Default TrueType Font: After this Key Name you will find a Windows TrueType font name which will be used by ArchiCAD both in the Floor Plan and in the dialog boxes whenever a desired font does not exist, is missing or has been deleted. The most important effect of this Registry entry is that if you import an ArchiCAD project file from another platform (e.g. MacOS), every font name that is used in the ArchiCAD project but doesn't exist in Windows will be displayed with this default TrueType font. If the font name defined by the Default TrueType Font Registry Key Name is also missing from the system, the Windows default GUI font will be used instead.
Large Dialog Font: The Key Value defined here is used in ArchiCAD dialog boxes for any text whose size is at least 12 points.
Small Dialog Font: The Key Value defined here is used in ArchiCAD dialog boxes for any text whose size is 9 points.
Example of the default values of the ArchiCAD Windows Registry keys:
Default TrueType Font "Arial"
Large Dialog Font "MS Sans Serif"
Small Dialog Font "Arial"
Erika
Architect, Consultant
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