Let me make sure I understand what you're doing.
"If I open a LR imported and adjusted image in PS for some work and make a lens distortion correction in PS and then save it back to LR"
Do you mean that, in LR, you choose "Edit in" and then choose "Edit in Adobe Photoshop CS6...". Then, after editing, you choose "Save changes...", and so back in LR you have the original file in LR, and in addition a new TIF or PSD created in Photoshop.
And you're saying that if (in LR) you look at the new TIF or PSD created in Photoshop then you can't see the results of any edits done in PS? Do you mean that the new TIF or PSD looks identical to the original file in LR?
If I've got this wrong, perhaps you can explain in detail the exact workflow how you go from LR to PS then back to LR.