It appears that they may not be entitled to their attorney's fees being reimbursed if they win, so it may not be wise for them to sue. 

I had to pay the property taxes, HOA, and insurance on my own (which the tenant reimbursed).

According to the property code, Section 34.21 you are only allowed reimbursement for expenses "for maintaining, preserving, and safekeeping the property" which would include insurance, legally-required repairs, payment of municipal liens imposed for health or safety reasons, HOA dues, and utility impact or standby fees. 

Or if you really want their property you can try to help them out with waiving or reimbursing some of those fees to get them sooner.

First, is to drop the payment for excess electricity and reimburse through some federal credit at about 1/3 the rate.

There's a lot to unpack in your post.Retail/Industrial/office are all very different in terms of economic outlook, investment thesis and operations.NNN does have reimbursement for operating expenses.

In the end, you get full reimbursed for the full rehab, so the loan pays for it.

I pay the utilities and they reimburse with the monthly rent. 

You can pay it from your personal credit card and then, if necessary, reimburse yourself once the business is operational.

They also probably don't want to take the risk of not being reimbursed.