To see whether there even are unexpected characters, assuming your pasted content is in A1:
Select/mark cell range B1:L1 (or however long enough for your A1 cell content), then (with the active cell still being B1) enter
=UNICODE(MID($A1;COLUMN()-1;1))
and close the input with Alt+Enter. That distributes the formula over the selected cell range and outputs one Unicode character code value in each cell. Extraneous (selected range longer than cell content) display Err:504, ignore those. To convert back for easier investigation you could do similar with a selected cell range B2:L2 and in B2 the formula
=UNICHAR(B1)
again closing with Alt+Enter.