Lightroom Classic - Same Exposure images different results with same adjustments

Here is my issue I am facing and hope somebody can help me or explain it to me. I took some room photos. The rooms have only 3 walls so the inside is darker then the outisde. So I expose my camera for he outside and then take several images with the same settings one base iamgage with out a flash and the rest using flash to brigthen the inside walls, furniture etc. In Lightroom I pick the once  I want and  adjust the expoure etc for the first image. (no flash image) I then copy the same settings to other images with the flash trying to keep the exposure for the outside but all the outside exposures getting brighter especillay in images where I have more flash or brighter flash in forground. should the outside exposure  not stay the same as no flash hit the tree or the sky . but it is sometimes 1 -2 brigther (depnding how bright the flash is in the image) then the no flash image even so all settings in the camera and in lightroom on each picture are the same .  Like in the no exposure image I can see the clouds and the blue in the sky and then when i copy the same settign to the flash image the sky is completly blown out . Hope some body can explain