The FSC curves could be normal. Are your particles downscaled for the refinement? What were the pixel and box size upon extraction and what box size did you use for the refinement job? Note that the default value for heterogeneous refinement is 128 px. So, if your new pixel size is ~2Å and the data are good, it would be normal that the curve doesn’t drop to 0.
With that said, the real space slices don’t look great and I guess the volume presents artifactual stripes when you open it in chimera (?). Also, the 2D averages below present artifacts (these weird pentagonal “donuts” that make them look like a mosaic). We also have seen similar artifacts in my lab. I think the cause of this is failure to correctly align the particles, possibly due to huge variability, resulting in “overfitting”. It looks like you have a small membrane protein in a nanodisc (?). So the inner protein features are too little to guide the alignments and the outer scaffold protein is too variable (in conformation and size) resulting in these blurred averages. Good luck!
Probably others have more to say about this and I’m very curious to read what they have to say. In any case you should not trust the 2D resolution, at 4Å you should be able to clearly see secondary structure features, which is not the case.
Hope this helps,