It might depend on Scopus or WoS, but maybe it might be recent. If it is recent it may take a time. I would like to say RG counts the metrics in a particular way, it would be best to reread the counting and the citations, and yes, we all mean the same by citation. i think most of the questions would be due to RG and not by a mistake, which might also happen. It would be a matter of asking if there was any difference, with the submission or load of the preprint/ article you intended to publish.
The total citation depends on the database used, for example, RG counts all citations from the papers on RG. So if you have cited by other paper not added to RG it will not be counted. Google scholar shows the highest number of citations as all published papers could be found by google. When you moved to Scopus you will find a lower number of citations as it counts only the papers indexed by Scopus only. Same if you go to Thomson Returnees u will get lower citation as it counts from papers indexed by WoS only.
You can only get the same number of citations in RG and google scholar in case all of the papers have been cited you were registered and added to RG.
I am sure your real number of citations are greater than that indicate in Google Scholar or ResearchGate. Catching all the citations exactly is an impossible thing to carr-yout. All citations listed in Google Scholar or ResearchGate is done based on their catching limitations. All computer applications have their own limitations.