Hi, "Get Items" returns only 100 entries when "Top Count" box is left blank. Hint in "Top Count" box says "Total number of entries to retrieve (default = all)". I would expect that leaving the box empty will return everything.
Also, if there is some limitations, like max 5000, the hint in "Top Count" box should says something like "Total number of entries to retrieve (default = all, up to 5000)".

Ref:
https://powerusers.microsoft.com/t5/General-Flow-Discussion/Flow-Get-Items-returns-only-100-entries-...
Thank you,