Very interesting problem.  It is Excel trying to be helpful and translating
numbers that might be dates into dates.

Biff's formula is looking for strings that look like numbers.  When you have
certain values in the second group, the values that the formula is returning
include 10-37.  That gets interpreted, on your machine, as 10/1/37 (October 1,
1937) and the value of that is 13789.  Similar with 11-37 and 12-37.  Of
course, 13-37 cannot be interpreted as a date, so in that case only the number
13 is returned.

One method is to eliminate the "-" from your string, substituting something
that will never appear in the string, and can't be misinterpreted by Excel.

So group 2 would be:

=LOOKUP(1E+100,--MID(MID(SUBSTITUTE(A1,"-",CHAR(1)),FIND(
CHAR(1),SUBSTITUTE(A1,"-",CHAR(1))),255),MIN(FIND({0,1,2,3,4,5,6,7,8,9},
MID(SUBSTITUTE(A1,"-",CHAR(1)),FIND(CHAR(1),SUBSTITUTE(
A1,"-",CHAR(1))),255)&"0123456789")),ROW(INDIRECT("1:255"))))

You could make similar changes in Group 3, but it shouldn't be necessary given
the format of your data:

=LOOKUP(1E+100,--MID(MID(SUBSTITUTE(A1,"-",CHAR(1)),
FIND(CHAR(1),SUBSTITUTE(A1,"-",CHAR(1)),FIND(CHAR(1),
SUBSTITUTE(A1,"-",CHAR(1)))+1),255),MIN(FIND({0,1,2,3,4,5,6,7,8,9},
MID(SUBSTITUTE(A1,"-",CHAR(1)),FIND(CHAR(1),SUBSTITUTE(
A1,"-",CHAR(1)),FIND(CHAR(1),SUBSTITUTE(A1,"-",CHAR(1)))+1),255)
&"0123456789")),ROW(INDIRECT("1:255"))))

Personally, I would use a User Defined Function to pull out the digits, but
some IT departments don't like that.

Also, you did not specify what you wanted to extract for the third group which,
in these later examples, are mixed digit and non-digit:

S10754-10-379A617

Biff's formulas, as modified above, return

10754
10
379

Is that what you want?

--ron