ISC Exempt or Liable - urgent help needed

[ramiri]

My first CoS was issued in 2015, then I had a new CoS for a 5 months extention in 2018 all in PhD level job codes which are ISC Exempt.
Now I am changing employer under another SOC, is the new CoS ‘ISC EXEMPT’ or ‘ISC LIABLE’?
Very urgent answer needed. Many thank in advance for your help.

[cracker1234]

You are exempt from ISC.
New visas after 6th April 2017 are subject to Immigration Skills Charge(ISC).

[ramiri]

My confusion is coming from paragraph (d) in section 7 of ‘The Immigration Skills Charge Regulations 2017’ where it states:

Transitional provision
7. A sponsor is not subject to the obligation to pay the charge where—
(a) the sponsor assigns a certificate of sponsorship to a skilled worker who was assigned a previous certificate of sponsorship as a skilled worker before these Regulations came into force;
(b) the skilled worker made an application which relied upon the previous certificate of sponsorship referred to in paragraph (a) which resulted in the grant of entry clearance or leave to remain;
(c) the skilled worker undertook the role in respect of which the entry clearance or leave to remain was granted; and
(d) the skilled worker has not ceased, since being granted the entry clearance or leave to remain referred to in paragraph (b), to have leave to enter or leave to remain by virtue of an application made as a skilled worker.
http://www.legislation.gov.uk/ukdsi/2017/9780111154663

all the 4 criteria are applicable to my first CoS but what about the 5 months extension I had recently. The new CoS for this extension was issued after April 2017, doesn’t this change the situation?
Has anyone been in this situation?