Unpaid Leave on H1B: What Are My Options

I am on an H1B visa and recently switched to a new employer. Due to some delays, there was a gap before I started receiving payroll. I am exploring the option of unpaid leave for this period and have a few questions:

  1. Under H1B regulations, is unpaid leave allowed only for medical reasons, or are there other acceptable reasons for unpaid leave?
  2. If unpaid leave is allowed for medical reasons, what specific documentation is required to support this?
  3. Are there other situations (e.g., personal reasons, lack of a project) where unpaid leave is acceptable under H1B rules, and what documentation is needed in those cases?
  4. Does USCIS need to be informed about the unpaid leave period? If yes, what is the correct process to ensure compliance?
  5. How can I demonstrate that the employee-employer relationship was maintained during the unpaid leave period?
  6. Will this unpaid leave or payroll gap potentially affect future H1B transfers or extensions?

Any guidance on this matter or shared experiences would be greatly appreciated. Thank you!