I use Windows11. Got RT 5.11 and Gimp 2.10.38.
I have used RT for years before sending TIFFS to be finalised in Gimp.
In RT I have a custom processing profile set to open when I import a new raw file, then I adjust said file and then export it 16Bit. and open it in Gimp.
Lately, in Gimp I used a text tool over the gimp opened image, which will now only write in green colour. This never used to happen before, (I only just noticed it recently). However -
…if I open the raw file in RT with the NEUTRAL profile, and then do adjustments and then send it to Gimp, then the text tool will write in my chosen colour.
I asked about this in the Gimp Pixls.us Discuss and also in a Gimp forum. A Gimp reply talked about a ‘colour indexed image’ but I think the problem is in my RT settings or…
Can someone can help here?
Could you post that profile for us to look at?
and then export it 16Bit
what file type and what output profile?
OK - So with more fiddling around I notice that my ex RT Gimp images are opening in 16Bit Integer under image-precision. When I change this to 16Bit Float everything is OK again. And when I change this to 8Bit Integer or 32 Bit Integer or Float its OK & the text tool writes in the colour I choose. 
I’ve been at this all day and am nearly happy. It seems I was exporting them from RT in16Bit Integer, and Gimp doesn’t like that. Thanks for your help.
I’ll post it to you. You mean the ex RT file and the
IMG_0122.tif (57.6 MB)
IMG_0122.tif.out.pp3 (22.1 KB)
.out.pp3 file?
Yes, thanks.
No help, but I tried your TIFF in the GIMP 2.10.34, and text came out default white at any setting of image precision.
As to the .pp3, I notice that your RT output profile is set to ‘RTv4_Large’, whereas I have mine set to RTv4_sRGB -not that that should affect the text color …
Its next day here. Thanks for looking into it & your help. Appreciated.