Answers from CIC website:
Can I count work experience that was part of my education toward the work requirement?
No. Co-op terms and apprenticeships completed before graduating do not count as skilled work experience. They are considered part of an educational program.
The work experience you can use to apply for the Canadian Experience Class must not have been gained while studying full time on a student permit (for example, experience gained while on a co-op work term).
I think Research/Teaching Assistantships definitely fall under the no category (co-ops and apprenticeships). I’m not so sure about the CPT thing. If you want to be sure you could get a letter from the university saying you had completed all requirements for graduation except capstone in Aug 2017 as well as add the offer letter you might be able to get past this strict requirement. Did you earn a credit for CPT? If not then really it wasn’t related to getting your degree.
Honestly, CIC is never going to ask you for your visa status while working on a particular job. You can be honest and submit the CPT as a full-time paid work experience at the same time add your degree whenever you did it. This way you are being totally honest and best case they ignore it and give you points, worst case they dont. Any way you have a good enough score to nudge past the latest cutoff without the CPT.
The important sentence here is They are considered part of an educational program. In that sense even OPT is considered part of a program even though you have graduated and CIC accepts it. But then one can make the argument that you were already qualified to do the work related to both the CPT and OPT when you first got qualified to work in this field. i.e. after Bachelors.
Other questions I came across on their FAQs
Can I count part-time work toward the work experience requirement?
You can count part-time work toward the work experience requirement, as long as you were not a full-time student at the time.
However, you must have gained the equivalent amount of experience as someone who worked full-time for at least one year (1560 hours)
Your work experience must be:
in the same type of job as your primary NOC
within the last 10 years
paid work (volunteer work, unpaid internships don’t count)
at skill type 0, or skill levels A or B of the 2016 National Occupational Classification (NOC)
at least 1 year (1,560 hours total / 30 hours per week), continuous:
full-time at 1 job: 30 hours/week for 12 months = 1 year full time (1,560 hours)
equal amount in part-time: 15 hours/week for 24 months = 1 year full time (1,560 hours)
full-time at more than 1 job: 30 hours/week for 12 months at more than 1 job = 1 year full time (1,560 hours)
Even the positions mentioned on my Reference letter would make be like Software Developer Intern.
I had added all my 3 internships I did during Masters and PhD (CPTs,OPTs) and they accepted it. I think you should be honest and add everything properly (with reference letters etc.) and let IRCC decide.